Having problems with cops around my neighborhood, lots of noisy cars and complaints. I'm considering going back to stock catback, but wondering if it will hurt performance a lot. What is the piping diameter on 88-91 Si? cant remember it's been too long...
Thanks

 

if u have turbo u can have alot horsepower gone but not 2 much..we have the same problems everyone who races on are block cars are loud cops are regualers...

 

stock is 2.25

 

No its not...

 

WIll feel a MASSIVE loss. Get an es oval man.

My buddies got one and it has a sick sound but when he gets pulled over for other things they usually check the exhaust right? ES Oval looks stock and if he says it was loud my buddy says it has a hole and the cop always believes.

Edit: Stock is not 2.25, I think its 1.5 maybe a 1.25, cant remember

 

Yeah I forgot the B16 is NA stock + intake. If I remember, stock piping is around 2'' crush bend. Wondering if 2.5 crush bent would be too big for this application?