i was wondering if i do a header on my stock integra with stock exhaust will it be loud or still a nice stock sound? will i notice any difference in power?

 

I am running a 4-1 on mine with stock exhaust. Wont be loud at all. Mine somewhat sounds stock, I can still hear my short ram over the exhaust even with a small leak at the axleback.

 

You shouldn't expect noticeable power gains with an otherwise stock exhaust. However, having the header on will produce larger gains if you do upgrade the exhaust.

 

Can I keep the stock cat by doing an aftermarket header? Havnt looked under the car yet to see where the cat is...guessing the header bolts to the cat.
On my zx3 focus the header bolted up to the actual exhaust so you had to weld in a cat if you wanted to keep it