With the HKS, the test pipe amplifies the awesome sound the HKS already makes. However, any dual system with a test pipe will still be quieter than most singles with the cat in place. ...at least the Buddy Club.

 

You might want to read this thread, as it speaks to the issue of an O2 simulator, as well as some other proposals for dealing with the MIL.

https://www.s2ki.com/forums/showthread.php?...22&pagenumber=2

 

But does anyone know if I still use stock ECU, what will happen?
(no money to buy aftermarket ECU right now )

 

You will have to look at the CEL...

Nothing will be damaged.

 

sorry, a stupid question. What is CEL..
You mean I wont hurt the engine at all if I use stock ECU?

 

[QUOTE]Originally posted by b8b88
[B]sorry, a stupid question.

 

how loud is the straight pipe?

 

if you got use to the stock ones then straight pipe is going to be very very loud = easy to get put over by cops.

 

S-Duces, I'm assuming he's going to run his straight pipe into some sort of muffler, like A'PEXi N1s (which is what I've got). If so, I don't think the straight pipe is going to make that much difference. For me, swapping out the cat with a straight pipe didn't increase the noise by nearly as much as swapping out the stock mufflers for the less restrictive muffler. My car sounds like an all-out race car on WOT. That's both the good news and the bad news. Sometimes, it's just obnoxious.

 

I run Mugen header/exhaust with spoon de-cat, not much louder than stock untill v-tec, the tone throughout is different though.