Lexus IS Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter #1
Hey Guys. Really need some help. My Aristo Swap 2jz gte twin turbo IS300 had 3 inch straight pipe with catback at 14.5 PSI. Unfortunately, I had to change my exhaust to 2.5 inch with filters due to law issues and I saw the PSI drop to 7 PSI and I have lost significant power. Is there anyway to get back the boost which I had before without changing my current Exhaust?
 

·
Registered
Joined
·
785 Posts
Changing exhaust size will have an effect on boost pressure, you are restricting how fast the gas can be pushed out of the exhaust. On a turbo 4 cyl car i had years ago going from factory (maybe around 1.75" to 2.5" jumped the boost from factory 7psi to 12psi purely on the increased flow allowing the compressor to spin faster.

What are you using to govern the boost pressure?
 

·
Registered
Joined
·
3 Posts
Discussion Starter #4
Go back to 3 inch full exhaust. Get a good muffler. By the way, what is "Filters"?
Unfortunately I cant. The sound of my exhaust is too much. It is actually louder than a Mustang. Which makes it illegal. And it is very close to backfiring as well. By filters I mean a muffler box and a resonator.

Is there any other way, without changing the current exhaust setup that I can bring back the psi?
 

·
Registered
Joined
·
3 Posts
Discussion Starter #5
Changing exhaust size will have an effect on boost pressure, you are restricting how fast the gas can be pushed out of the exhaust. On a turbo 4 cyl car i had years ago going from factory (maybe around 1.75" to 2.5" jumped the boost from factory 7psi to 12psi purely on the increased flow allowing the compressor to spin faster.

What are you using to govern the boost pressure?
I dont have control over the boost pressure. I know the flow is restricted because of the resonator and the muffler box (Its illegal for a car to be that loud). What I want is to get 14psi boost with the current exhaust setup without increasing sound again. Is that possible?
 

·
Registered
Joined
·
2,786 Posts
Unfortunately I cant. The sound of my exhaust is too much. It is actually louder than a Mustang. Which makes it illegal. And it is very close to backfiring as well. By filters I mean a muffler box and a resonator.

Is there any other way, without changing the current exhaust setup that I can bring back the psi?
You can. You need the right mufflers. Look at the Greddy Supreme SP. Or do something custom. But you can get the sound level down.
 
1 - 6 of 6 Posts
Top