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Discussion Starter · #1 ·
Hey guyz,

I have a really simple question. I have an 88t supra (7MGTE) and it has intake, Bov, and the rear muffler changed to straight through. I also have a MBC and would like to run 9psi. Now going from the stock 2 1/4 inch??? exhaust piping to a 3 inch cat back piping system, would that make a huge difference? Your only opening it up by 3/14 of an inch, which doesnt seem much, but I'm curious if I will notice a difference, bothy on stock boost and 8-9 psi. I dont wanna go and spend $250 AUS if its not going to make a difference that I can notice. And will it change the exhaust note much? It kinda sounds like a V8 now with lumpy CAMS, not a nice smooth note, but I guess thats coz the engines got 24valves?


Thanks guyz
 

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"DANNY TANNER!!!"
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1,847 Posts
3 " exhaust will give you decent performance, but it's the most important if you want to go for tons of power. Just picture humas blowing through a coffee stir stick. Not much flow and a lot of struggle. We struggle to breath and eventually tire out. Same concept with the turbo/
 

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I live in a giant bucket.
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1,237 Posts
I'm not willing to run anything higher than stock boost till i replace the exhaust from the turbo back, not just a catback.The stock elbow is horrible, just horrible.
 
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your increasing the volume of available gas flowing space, 3/4 on an inch is not all that is being increased....its a great deal more than that...use the formula for a fixed volume of a cylinder as an example using 2.25 as the diameter, and then 3, you will see the difference is bigger than 3/4 of an inch. You will notice a difference also, quicker spool.
btw, not to be a search cop, but you prolly wanny try searchin around a bit for exhaust, there's a whole sticky thread about exhaust FAQ's....
 

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It will make a noticeable difference. Most aftermaret exhausts are straight through unlike the stock mufflers. Plus eliminating cats, if this applies to you, can add more power. The stock system is extremely resrictive. At some points i think it gets to around about 2'' in diameter.
 

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Just say no to Supras
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Fabbz said:


Now going from the stock 2 1/4 inch??? exhaust piping to a 3 inch cat back piping system, would that make a huge difference?

Absolutely. Its 'only' a 3/4" increase in diameter (plus it will be mandrel bent), but that equates to a 56% increase in area (from 4 to 7 square inches)
 

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ma70-7m=1JZ
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Yes it will make a big difference. But if you get a 3" downpipe and full 3" exhaust, it will feel like a different car, it will pull harder in the higher revs, and not just die off the a stock car does at 5000 rpm. The turbo will also spool up alot quicker. You should also get about 1-2 psi more boost just by opening up the exhaust. A full 3" system should get you around 30-40 hp more than stock.

3" exhaust is one of the first performance mods one should do.
 
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