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Discussion Starter · #1 ·
Whether it's a muffler or resonator, I'm looking for the unit behind the axle.

Does anyone make a twin tip (w/ or wo/ resonators) 'muffler' with a right side inlet that will fit back there? Done all the requisite searches here and web surfing but just haven't found the right answer or supplier yet I guess. I have a long tube header on hand and about to put in a custom system. Two plans:

Muffler as described above with constant diameter pipe up to the header. If muffler with tip resonators is still too loud a glass pack or similar can go in forward of the axle.

Other plan is from the header back to a Flowmaster 40, up and over and into a pair of chrome tips - with the option of stuffing with resonators.

Specific question: Opelwasp - the 11" Dynomax muffler you mentioned 4 weeks ago - do you have a part number for it? I hate dealing with them folk with out something specific to start with (also haven't gotten back on the Summit page to check this specific unit out, but it's next on the to do list).

Forum: the muffler style I described above, is something like that available and where should I look? Domestic or European? Haven't a clue where to look overseas.

New rim and tire choice for the GT worked out great due to the info gained from y'all. Sent photos to my dad yesterday (30 year prior owner) and he liked to cried he thought it looked so good. Over a dozen people came up to me today at work after seeing it commenting on what a fantastic looking car it was. VERY happy. Exhaust system is next and would appreciate your put before diving in.

doug

Wonder how he's going to react to the turbo next year?
 

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I went with your "Other plan"..... I don't have a header but I put a Magna Flo (#12237) in front of the axle then up and over to a pair of chrome tips (one functional, one fake). It sounds pretty good but after about 3000 miles now.....I wish it was quieter. I'm not sure what to use to quiet it (just slightly) that will fit behind the axle and not hang down too far.
 

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Opel exhaust

Doug;
If you don't mind a "little" drive, you can buzz over to the MIDAS on Buford Hwy, in Doraville, GA. The owner is Dennis Kerr, I have made him an Opel exhaust expert over the years ;) As I'm the only one that ever goes in there. over 15 years ago, he did my GT. stock head pipe, back to a MIDAS gold muffler (in front of the axle) and bent a pipe over the axle and made a special "U" shaped pipe to match the openings in th back, with chrome pencil tips. He used h/d hangers on the muffler and the car has never been back since it left the shop 15+ years ago. The sound is nice, not "farty" like the rice burners. Two years ago he did my Sportwagon in very much the same way, but, I supplied a ANSA tip I got off ebay. Then about a year ago, he did my wife's Sportwagon in the exact same way, both sound great!!
 

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Discussion Starter · #4 ·
Thanks guys. Just got back from the shop that will do the work next Friday.

Over the weekend I will surf around to get some vendor data and then I'll go hit a couple of the places local to me to pick up what I need; the muffler, tips, real hangers, and some flanges. I'll flange the header connection and the backside of the muffler in order to easily remove this assembly if necessary for room during future maintenance.

We chatted and decided to run 2.25" pipe from the header to the muffler, then 2.5" over the diff to the tips. Should look good, sound good, and be solid. Tips will incorporate removeable resonators.

At least it sounds like a plan. Time to go jack it up and take a hard look at the underside to see specifically what I have to deal with. Header will also go in this weekend. Gona be fun driving the 25 miles out to the shop for the pipe work with an open header.

I haven't read the book yet and I haven't broken out the flashlight and mirror to inspect, but I assume R&R of the intake and exhaust manifold is pretty cut-n-dry. Anything noteworthy that can cause trouble?
 

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Things to Do

Just check that the thickness of the header flange is the same as the thickness of the area of the intake manifold that the attaching bolts nip up on. They must both be nipped up together to get a good seal on the manifold gasket. If the thickness is different build up the header flange to the same width.

Oh! And use a new manifold gasket. Don't over tighten the bolts and use some anti-seize on the threads. Check the bolts next day after running the car; then a week later; then at least every service interval.
 

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Discussion Starter · #6 ·
Exhaust is done. Header, 2.25" pipe back to Flowmaster 40, 2.25" up and over and into a pair of 2.25" chrome tips.

Just what I was looking for. Sounds bad a... very throaty and probably a little louder than most would care for but as far as I'm concerned it's perfect - and ready to accept a fresh motor with a healthy cam amongst other things next year when it gets attacked to fix the oil leaks.
 

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Wood95SS;
I guess I am a little to late for you, but just in case someone else requires a muffler for their GT here is some info for stock mufflers. This is the one I purchased for my GT in 1993 and it is a Walker Muffler, part number 21845 with a Lifetime warranty (Walker Manufacturing Co., 1201 Michigan Boulevard Racine, WI 53402). My assumption is there is a good chance they are still available (hope so for my warranty?). I had a loan of a digital camera and so have included some pics.
 

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4ZUA787
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665 Posts
thats exactly how my 72 gt exhaust looks with those same tips i thought they were custom due to the fact the tips had big welds on them were they connect and one of them was crooked a lill and i had to bend back.
 

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tips

put some Hooker resonator tips on it 3" and it will sound sweet. the tips smooth out the tone so it isnt so harsh.
 

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Finished Exhaust sound

Wood95ss -

I was wondering if you could send or post a sound file of your new exhaust...I am exhaust-less right now and will be installing new custom exhaust within the next couple months. I am looking for muffler that won't be too loud on interstate driving but will give me a nice tough sound...
 

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exhaust

cbehm;
A midas muffler has a real nice sound to it, not loud, but, has a note when you get on it. Not like the rice burners. There's a Midas Shop in Doraville I have been doing business with for years and he has this sytem down pat for me. Plus the system lasts. My GT still has it's system he put on ober 15 years ago and it has never been touched since. He has done this to both my Wagons, and a friend's GT.
Gene
 

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OPEL-LESS!!!
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it might be just me, but i love the way my GT sounds. not to dog anybodys GT i've seen, but i like the sound of mine over just about any body elses GT. i just have a stock exhaust header pipe, front muffler eliminated, and using only the stock rear resignator. it had a deeper pitched sound that most of the other "pingy" GTs i've heard. its fairly quiet, hear no exhaust going down the road, you can barely hear it when you get on it hard, but it sounds so awesome at idle and on the downshifts or just slowing down in gear, has a rumble like cackle to it. i'd post a sound file if i knew how, but even if i did i'm not so sure i have the right stuff to record it.
 

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Discussion Starter · #14 ·
Cbehm - I'll see what I can do about a sound file over the coming weekend. Still busy from this past weekend replacing the fuel system from the tank outlet to the carb inlet; electric pump, press regulator, and gauge. What I removed was rather revolting. Dumped the mechanical pump and fab'd a blockoff plate too.

This exhaust: I love it but to be honest I think it would be unbearable for most. Couple guys at work listened to me pull in and asked me what I had in the car in that it 'sounded' like a V8; I told them it was a low compression 4-banger with half of the exhaust system I have in my SS - which is the sound I was looking for. Very throaty; sounds like it actually has a pair! [it will after the rebuild as I intend to up the compression to 10.5:1 and cut a cam similar to the GM LT4 Hot Cam in my SS. This should handle the forthcoming G5 speed conversion nicely].

Final comment: Ultimately I may lock on to a set of the ref'd Hooker resonators as I'm bound to get busted sooner or later along with the younger fellers in their windup toys for making too much noise on the weekend evening cruise circuit. Taking it easy I can control the decibel level to some degree but if you are anywhere close there's no doubt in your mind as to who just went WOT.

PS: dad baby'd this car rpm-wise. I recently started stretching its legs; boy, even with low cylinder pressure (110 psi) across the board this engine 'wakes up' at 5,000 rpm! Almost like another carb secondary opening. Can't wait to go thru this mill and build it up. This little GT is going to kick some serious butt.

"And how would you like your clock cleaned this evening? Via big car (6sp Impala SS), medium car (4sp Corvette), or little car (5sp Opel GT)?" aka 4-Door Vette, Real Vette, and Mini-Vette!
 

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The resonated tips are NOT going to be enough if you are trying to reduce noise level- Believe me, been there done that. I have almost the same setup, flowmaster 40 with a y-pipe at the back for two resonated Monza tips.

What really worked for my car was adding a 24" glass pack in front of the flowmaster. The car is quieter now, but it did lose that really mean sound at idle although it still sounds good a wide open throttle. A fair trade for not having my ears bleed (not to mention not pissing of the neighbors or cops).

-Nathan Acree
Albuquerque New Mexico
 
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