i just installed a jdm itr header and a carsound cat on my 2k gsr. i ran out of money to get an exhaust so i'm temporary using my stock b-pipe. my engine is basically stock with a cai. after the installation, i went out for a drive, and i notice a sound coming from under the car. everytime i rev pass 3.5 rpm i notice a "hisst" sound. i went home and on neutral, i rev it to 3.5 and let go the gas, i hear the same sound. it seems like its coming from the cat. the "hissting" sounds like a leakage or blow out valve (which i don't have)....does anyone know whats wrong?...everything seems to be tight...

also, i already reset the ecu after the installation...

 

it's normal, almost everyone gets the same results when combining the two. My header and exhaust is so raspy, but it's nothing to worry about.

 

Same noise here.

 

so whats causing the noise... the combo of the jdm header/cat or the cat/ b-pipe?
any power loss from the noise?

 

probably the bottle neck were the cat and the bpipe meet up they are mismatched

 

I had my bottleneck cut out, and a new flange put in.
-still makes noise.

 

it's the header, it makes that noise.

 

depending on the volume of the noise it could be that the flanges are not bolted tight enough.

have a shop hit them aith air tools

 

the fix is easy imo.

do this

step 1: turn the **** labeled "volume" on the radio to a higher setting

that's all it takes and the problem is resolved.

 

That's your answer to everything. I knew I should have kept those subwoofers from my other car

 

less mass = less ability to absorb noise from the motor.... that is why the valve noise is louder with the heder on.

 

just to "werid noise"/"rattle" complaints. We don't drive heavily overdampened lexus' here do we? expect some damned noises/rattles.

 

its just the blow off valve that comes with the cat

 

wow..free blow off valve...but then, its a little ricey b/c i don't have the turbo to back up that "blow off valve"...