i have resently put on a 4-1 header and spoon sports hi flow cat on my si. i have a really raspy sound in the note of the exhaust. the rear section is a thermal r&d mid pipe and axle back. be4 i put the header and car on it wasnt raspy. is this just from freeing up the flow? my si has a 98 gsr swap so it screams but the raspyness is at like 4500k-5500k. is that normal?

 

i have the 4-1 jdm itr header on my car and its also raspy...and have noticed that a header does cause a rasy sound on other cars when installed..a header doesnt insulate the sounds of the combustion chamber as much as a cast exhaust manifold does..hense the extra noise