replace stock muffler or?
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Thread: replace stock muffler or?

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    Senior Member terrylewisac's Avatar
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    replace stock muffler or?

    Hello all,
    After a few good rev's today before a ride we came back to notice black marks on the concrete
    my son and I found a hole in the muffler today on the bottom.
    I was going to temp patch it and order a new one later
    However my son wants to cut out the muffler and install a thrush glasspac
    Has anyone done this if so how did it sound?
    Or have you used something else as a replacement?
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    Just Some Dude in Jersey The Scifi Guy's Avatar
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    It will sound like crap with a Thrush glasspack.

    I suggest getting a new regular muffler from OGTS. Keep it simple at this point in your build.

    If you want to get fancy, then the ass-kickin' great sound way I went was to have a stainless Flowmaster muffler installed, a split Y pipe over the axle(I think Hondas use them), and then have the shop make 2 exhaust pipes to fit the Y. You then buy high quality tips to put on them. Have everything be stainless so that you pretty much don't have to replace anything for a long time.

    IMG_5164.jpgIMG_5165.jpgNew Flowmaster Muffler and Split Exhaust 7-21-16 (1).jpgNew Flowmaster Muffler and Split Exhaust 7-21-16 (2).jpgNew Flowmaster Muffler and Split Exhaust 7-21-16 (3).jpgNew Flowmaster Muffler and Split Exhaust 7-21-16 (4).jpg

    I think the resonators are useless junk. They're not a muffler, they're just a hollow can made to try to add some balls to the sound of our engines. They fail miserably at it. The modern way to go is to shape the sound of your exhaust with your exhaust tips. Stainless steel also adds a nice low note.
    Last edited by The Scifi Guy; 12-08-2019 at 06:02 PM.
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    Opel Rallier since 1977
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    Be aware that as the glasspack erodes internally, the 'stuffing' can eventually come out. If you are lucky, it will blow out... if you are not, it will jam in the exhaust and plug up the engine operation. No foolin'..... seen it more than once. It'll take a few years. Never used one myself.
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    It sure does soiund llike crap

    I just fired up a car that I bought yesterday....and it has what was called a new exhaust...the muffler is one of those Trush pieces...the resonator is Opel... the exhaust is horrible...not a sound I could live with...raspy and loud...not good.
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    1000 Post Club tealcarver's Avatar
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    Terry check your PM's

    Bob


    Quote Originally Posted by terrylewisac View Post
    Hello all,
    After a few good rev's today before a ride we came back to notice black marks on the concrete
    my son and I found a hole in the muffler today on the bottom.
    I was going to temp patch it and order a new one later
    However my son wants to cut out the muffler and install a thrush glasspac
    Has anyone done this if so how did it sound?
    Or have you used something else as a replacement?
    terrylewisac likes this.
    71 Chrome Yellow GT

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    Senior Member terrylewisac's Avatar
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    Interesting guys Thank you,
    I put a glass pac on my v6 dakota and adjusted the carb to sound more like a v8.
    Seemed to work well in that application
    But a 4 cyl stock 1.9 opel
    First thing I told my son was no obnoxious rice burners in my garage
    If were to do something that's not stock it will need to be appropriate and ad to the harmonics
    Not just make it loud and ridicules
    If there's one thing I can't stand it's something loud and sounds like there may be something under the hood just to see it pull away so slow it can't get out of it's own way
    If you make it through an entire day and learned nothing you weren't paying attention

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    Senior Member terrylewisac's Avatar
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    Quote Originally Posted by tealcarver View Post
    Terry check your PM's

    Bob
    Perfect,
    Thank You Bob
    If you make it through an entire day and learned nothing you weren't paying attention

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    Senior Member terrylewisac's Avatar
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    Quote Originally Posted by The Scifi Guy View Post
    It will sound like crap with a Thrush glasspack.

    I suggest getting a new regular muffler from OGTS. Keep it simple at this point in your build.

    If you want to get fancy, then the ass-kickin' great sound way I went was to have a stainless Flowmaster muffler installed, a split Y pipe over the axle(I think Hondas use them), and then have the shop make 2 exhaust pipes to fit the Y. You then buy high quality tips to put on them. Have everything be stainless so that you pretty much don't have to replace anything for a long time.

    IMG_5164.jpgIMG_5165.jpgNew Flowmaster Muffler and Split Exhaust 7-21-16 (1).jpgNew Flowmaster Muffler and Split Exhaust 7-21-16 (2).jpgNew Flowmaster Muffler and Split Exhaust 7-21-16 (3).jpgNew Flowmaster Muffler and Split Exhaust 7-21-16 (4).jpg

    I think the resonators are useless junk. They're not a muffler, they're just a hollow can made to try to add some balls to the sound of our engines. They fail miserably at it. The modern way to go is to shape the sound of your exhaust with your exhaust tips. Stainless steel also adds a nice low note.

    Always a fan of the K.I.S.S. procedures.
    Keeps me in line and out if trouble
    Thank you Gordo
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    Just Some Dude in Jersey The Scifi Guy's Avatar
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    Looking at my pictures I see that I don't have a Honda or whatever style of split Y over the axle. I have the disconnect or coupling over the axle, but then just a single pipe bent to go to the driver's side exhaust arch and then another pipe grafted in on the bend of the first pipe to go to the passenger side exhaust arch. I don't know, I just tell the muffler shop what to do and they do it. You definitely don't want the first pipe to go to the passenger side in a straight line from the axle area and then try to splice in the second one to go towards the left side........all the flow will go to the passenger side. Don't do the resonator delete mod that way, do it the way you see in my pics.
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    Solo II is fun in a GT! okieopel's Avatar
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    Hersey! Glass Pack Mufflers are the way to go! They are loud, obnoxious and the chicks dig them.
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    Dan
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    Oklahoma Opel Preservation Society
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    Senior Member terrylewisac's Avatar
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    Looks to me like they did a pretty sweet job Gordo,
    They are keepers for sure nice work

    Thank you Okieopel if I were 20, 25 years younger glass pack for sure but my chick no diggy
    I can't even watch a good movie with the surround sound up with out it getting turned back down
    And the stereo in the Dakota, forget about it she wont even turn it on.
    7500 watts is way to much for her listening pleasure
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    Nice set up Gordo, I like it One of the first things I changed when I bought my Opel GT was replace the original muffler and exhaust pipes. Terry I went with the stock from OGTS and yes I kept the resonator. I would agree with you Gordo its useless, but doesn't sound bad. Next time I replace and probably not waiting for it to rust out, is to go with stainless and no resonator, but still keep it stock from OGTS.
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    Solo II is fun in a GT! okieopel's Avatar
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    Quote Originally Posted by terrylewisac View Post
    Thank you Okieopel if I were 20, 25 years younger glass pack for sure but my chick no diggy
    I can't even watch a good movie with the surround sound up with out it getting turned back down
    And the stereo in the Dakota, forget about it she wont even turn it on.
    7500 watts is way to much for her listening pleasure
    Got "Sennheiser RS120 On-Ear Wireless RF Headphones" for my Dad so he can watch TV.
    https://www.amazon.com/Sennheiser-RS...dp/B0001FTVEK/
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    Dan
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    1000 Post Club kwschumm's Avatar
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    Quote Originally Posted by okieopel View Post
    Got "Sennheiser RS120 On-Ear Wireless RF Headphones" for my Dad so he can watch TV.
    https://www.amazon.com/Sennheiser-RS...dp/B0001FTVEK/
    I've got a set of those. They are comfortable, work quite well and the batteries are easily replaceable with generic rechargeables. My only slight disappointment is the tuning knob is quite sensitive and can be a little finicky to adjust, but if once set it works fine. He will like them.
    Thurston County, WA, effective motto: "Gophers, Gophers Über Alles"

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    OpelGT.com Übermoderator kwilford's Avatar
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    Thanks to Mike aka opellane, I acquired an almost NOS stock'ish exhaust system for my Opel GT restoration last year. I installed it this past week, with a few improvements.

    My engine is fairly stock, with stock forged rods, 40 thou over forged flat top pistons, stock valves, an OGTS Combo 0.420 Hyd cam and modified cam gear w/ the Comp Cams offset bushing (set at 4 degrees advanced). I'm running a 38 DGAS on a quite modified stock intake (tented floor, welded and radiused ports and matched openings). Exhaust manifold is a Sprint, so less issues of heat transfer to the intake. I also wrapped the Spring and down-comer to reduce engine compartment temps. That might reduce the life of the down-comer, but I can accept that. The flywheel is lightened (19.4 lbs down from 23.4 lbs) with a stock clutch, and the entire rotating assembly was dynamically balanced to a tenth of a gram. I expect ~100 Hp and perhaps 110 ft-lb at the wheels. I have a Getrag 5-speed to keep the rpm at a decent limit on the highway.

    The stock 1 5/8" pipe is quite restrictive, perhaps more so than the Walker muffler and Bosal resonator that came from Mike. And especially as it leaves the two-to-one down-comer collector, with multiple bends that crush the pipe a LOT. I also wanted to incorporate a wide-band AFR system to assist in carb tuning. My goal was "drive-ability", not peak performance. While I enjoy a throaty exhaust sound, the novelty wears off after a couple of hours on the highway. Driving fun places in Canada usually entails big distances and LOTS of hours....

    A Calgary friend, Sterling Rempel, has an Opel GT with a similar drive-train. He bought it with an OGTS header feeding a 2" pipe, no muffler and a very nice 4-outlet ANSA resonator. It sounded great, but talking while driving was problematic. His solution, that I assisted with, was to cut in a 6" long flex joint just behind the header and stock muffler, but leave the rest as-is. It still sounds great, has loads of power, but doesn't make you want to wear noise-cancelling headphones on the highway

    So unless/until I upgrade to a stroker 2.4 (and MegaSquirt etc etc). I elected a similar route, except my resonator is stock, and had all the 1 5/8" pipe replaced with 2" bent at a local shop. Cost $58. Canadian, so like 10 bucks.... Fired up the MIG welder, added a couple of meaty flanges to assist installation, and replaced the weak exhaust hangers with decent ones to keep the system close to the body.

    I am a month or two from first firing of the engine, but I am confident that this exhaust system will work, and sound, terrific.

    Here's some photos:
    Attached Images Attached Images
    Last edited by kwilford; 2 Weeks Ago at 03:18 AM.
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    Keith Wilford
    Finishing up a bare-metal, nut & bolt rotisserie restoration of my '71 Opel GT

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    Just Some Dude in Jersey The Scifi Guy's Avatar
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    Hmmmm.....a flex pipe section to act as a sound deadener.......interesting idea!


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    OpelGT.com Übermoderator kwilford's Avatar
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    Quote Originally Posted by The Scifi Guy View Post
    Hmmmm.....a flex pipe section to act as a sound deadener.......interesting idea!
    Not so much a "sound deadener", but I believe that the flex pipe reduces the physical engine vibrations and such otherwise imparted to the exhaust system and then to the body. Less "NVH" (Noise-Vibration-Harmonic)
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    Keith Wilford
    Finishing up a bare-metal, nut & bolt rotisserie restoration of my '71 Opel GT

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    Senior Member terrylewisac's Avatar
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    Quote Originally Posted by kwilford View Post
    Not so much a "sound deadener", but I believe that the flex pipe reduces the physical engine vibrations and such otherwise imparted to the exhaust system and then to the body. Less "NVH" (Noise-Vibration-Harmonic)
    well said & WOW that is bbeeuuttiiffuull you almost don't wont to put it in and get it dirty it's so clean
    Very nice Mr. Kieth
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    Senior Contributor Site Supporter opellane's Avatar
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    Quote Originally Posted by kwilford View Post
    Not so much a "sound deadener", but I believe that the flex pipe reduces the physical engine vibrations and such otherwise imparted to the exhaust system and then to the body. Less "NVH" (Noise-Vibration-Harmonic)
    Wow, Keith that's some nice work Looks Great wrappin the Sprint Manifold... mum Have seen that before..
    I have my Sprint Manifold thermal coated or Ceramic coat to reduce the heat,, (Jet Hot mfg), I use the stock Heatshield and does a nice job with Vapor lock.. also run the fuel Line inside 3/4 heater hose up to carb.. Sleeve the fuel line with hose to protect from heat.. works great idea ..

    In my opinion I think when you increase the HP.. or Engine Performance Mod.'s ..Cam..Bigger Valve Bored Out, etc...
    Then the Exhaust should be increased to 2" Dia pipe for better Exhaust Flow.. to help make the motor Breath easier

    I have added the 2"S.S. Exhaust to my stock GT,, with a Weber 38/38 , Sprint Manifold and can tell you..it's like night and day..
    I had to just re-tune the Weber and it ran Awesome... In my opinion the costs to have a German Exhaust shipped to the states
    will always be better than any system a exhaust shop can make here ... The German Exhausts are Hand Made for the GT... and fits the GT perfectly.. am Very Happy with the system
    Attached Images Attached Images
    Last edited by opellane; 12-10-2019 at 06:30 PM.
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    1972 Opel GT, 1969 Opel GT, 1973 MGB,

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    Senior Member terrylewisac's Avatar
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    that's darn nice to.
    What does one give for a German shipment for all new exhaust? Just curios
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