THe HKS DOWNPIPE comes with a GASKET and 2 black RING which I didnt use. What are the BLACK RING for ?

 

That really sounds like you have a leak somewhere...

 

That might be your problem...

Also, when an install doesnt go the way I expected. I usually pull it out and try again from the beginning retracing my steps.

 

The blackrings are for the bolt. Look at the diagram. It shows it.

 

Did anyone ever figure out what that sound was? I just installed my hks downpipe and now get a whistle sound if I blip the throttle in neutral. I checked for leaks by popping the hood and smelling for exhaust, but it's clean. I stick my nose under the car to try to smell for leaks at the cat, none. I have a trained ear and nose when it comes to exhaust leaks, as I've have nothing but leaks on my 98 GSX (ghetto exhaust parts). I guess this sound is just coming from the intake. Now that the exhaust is pretty free flowing, it's probably just the sound of the turbo spooling faster.

 

My downpipe sounds OK and no noise or rattling. After my install, the sound when i rev is just like having a "headers" smooth sound. Check for leaks between the O2 housing and the donut o-ring, re-tighten the spring loaded bolts and most important, "align" the gasket between the downpipe and the cat then tighten the two cat bolts. Apply thin coats of anti-seize grease on the threads of the bolts before installing the bolts.

 

bumping a old thread for my question
just for clarification, the hks downpipe uses the stock donut gasket as well as the stock spring bolts?

 

i can't remember but im almost positive i had that when i installed mine. it is a leak between your o2 housing and downpipe. take off and try again. it probably isn't leaking when your stable but when you take off in 1st gear the engine is flexing and creating the leak between there

 

Yes it does,use the factory gasket and spring bolts.