2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.
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Old 06-01-10, 10:54 PM
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max exhaust size

so i know my exhaust is fairly large but i lifted my car and realized its HUGE. the smallest part might be 3.5 inches. it has an 18 inch resonator thats like 7-7.5 inches wide (o.d.) it sounds awesome has more of a raspy sound to it. but still i wonder how there can be any back pressure ,there arent any cats and the whole system is quite custom, some one even autographed with a stick welder. what are the rest of you running on your t2s?
Old 06-01-10, 11:13 PM
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I believe mazdatrix says no more than 2.5 inches, or you hurt exhaust gas velocity.

They have an exhaust narrative section that summarizes what you should do.
Old 06-01-10, 11:43 PM
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i'm running a racing beat 2.5" downpipe and presilencer to an apexi N1 catback, supports 300whp just fine.
Old 06-02-10, 01:34 AM
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3.5 or 4" will give you some performance benefits on higher horsepower setups, but it's hard to keep them quiet.
Old 06-02-10, 01:41 AM
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Ain't THAT the truth! I swear that it's glad that my shop was block from the local airport.... I was running 4" down and out to a Apexi 115 Dunk and GAWD....

Bad-*** for the top-end, though

I can MAYBE see 2.5-3, but not much more.

Any idea what your down ID measurement is ?
Old 06-02-10, 03:12 AM
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thats the smallest point ill take some pics tomorrow thing is easily bigger than the drive shaft in my exploder
oh and lets just say the car doesnt run perfect but gets from 4k 7.5 like it was 1 and 2 heres a vid not the best quality vid lg env3
http://www.youtube.com/watch?v=vNA0Lp82CIw
low revs
http://www.youtube.com/watch?v=5SOViwk4PAA

Last edited by bostonspgs; 06-02-10 at 03:18 AM.
Old 06-02-10, 03:20 AM
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the resonator is as big if not bigger than that muff an the rest is the same size as the tip all the way to the turbo
Old 06-02-10, 09:51 AM
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Nice.

As long as your ID is big enough to support airflow, no worries... It would change the tonal depth HORRIBLY to go smaller.
Old 06-03-10, 05:28 PM
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Originally Posted by bostonspgs
so i know my exhaust is fairly large but i lifted my car and realized its HUGE. the smallest part might be 3.5 inches. it has an 18 inch resonator thats like 7-7.5 inches wide (o.d.) it sounds awesome has more of a raspy sound to it. but still i wonder how there can be any back pressure ,there arent any cats and the whole system is quite custom, some one even autographed with a stick welder. what are the rest of you running on your t2s?
Back pressure is bad for turbocharged engines. Your exhaust may suffer from low velocity due to the large pipe diameter, but other than that it probably works just fine.

How big is the pipe that attaches to the turbo?
Old 06-03-10, 08:36 PM
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atleast 3.5 od to an s5 manifold i was thinking that the lack of bacpressure might make the engine wear more and cause it to die faster
Old 06-03-10, 09:47 PM
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The way your exhaust moves around like that, I'd say you need new doughnuts on the hangers. Speaking of which, is it hung properly to begin with?
Old 06-04-10, 12:29 PM
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Mmmmmmm... Dooooooughnuuuuuts.
Old 06-04-10, 01:27 PM
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yes and no given the size id say no because its mounted the same way as stock it moved like that and then a couple days later i found the tip in the sand with the welds on the back of the muff broken
Old 06-27-10, 08:41 PM
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bump, no just kidding heres a couple photos
Attached Thumbnails max exhaust size-004.jpg   max exhaust size-007.jpg   max exhaust size-008.jpg   max exhaust size-012.jpg  
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