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Discussion Starter · #1 ·
With a stock, but recently rebuilt, 1.9L what would be the best size exhaust? Two inch or 2.25 inch? I will be using the car for cruizing in sunny days and for autocrossing, so I am looking for more than just pure high rpm power.

Pete Sprenger
1972 GT
 

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Discussion Starter · #2 ·
Oh, by the way I did try and search for this information before posting, but I couldn't find anything that seemed to directly apply.

Pete
 

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OPEL-LESS!!!
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actually, the best thing i've found with my opels so far, is actually just stock sized pipe, with the front muffler eliminated with stock rear resignator

i have a 2" exhaust with header on my manta right now, raptor 2" muffler, quiet, sounds good, but no noticable gains over wide open header like there was with the GT. GT was gutless with wide open header but new exhaust woke it right up, smoother and torquier.
 

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i think its pretty much agreed here that its 2" all the way back, and 2.5" over the axle
 

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OPEL-LESS!!!
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you gotta have an exhaust to match the engine. you need a certain degree of backpressure int he exhaust for the motor to run smoothly and efficient. too much backpressure, and it just dont breathe, which looses all power. not enough backpressure, it'll idle rough, crappy throttle response, and takes what little torque you do have. the exhaust really needs to fit the engine, and type of driving you want to do, but brians exhaust looks VERY nice, i love it.
 

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You won't find much in the Racers Forum on stock exhaust systems, but have a look around where I moved this to. Many good posts, some excellent photos, a number of actual part numbers.
 
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