hey guys, i own an fd so i dont really cruise the 2nd gen forums all that much. i have a question to ask for my brother. i know that with turbo cars when you mate and extremely free-flowing exhaust up to a stock ecu and fuel system you run into more boost than you should be running. this turns into detonation. . . of course. now, my brother has a full exhaust consisting of full length, collected racing beat headers, a random technologies air-pipeless cat, and the racing beat upgraded cat-back. . . its a full exhaust. . . duh. haha. i just wanna know if theres anything BAD about running that exhaust on an otherwise stock s4 nonturbo. any help is much appreciated. . .

thanks,
paul

 

Well the only problem he might run into is not having enough back pressure to open up the 5th and 6th ports but it seems that he would with the cat on there.

 

The is an even chance you will want to rig the aux ports off the air pump.

 

Only if it's an S4.

 

Just a question but how does the "air pipeless" cat work? Does it not burn out like other cats even without an air supply?

 

 

the cat came like that from random. they offer it like that or with the port. dunno how long it lasts. . . just know that domestic cars run two cats on a true dual W/O an airpump.

as far as the ports go. . . the racing beat header is "supposed" to have enough to open the ports. i bought it for him a couple christmas' ago and that was my reason for purchase. . . thats why there IS cat or well replace it with resonator. who knows. . . just as long as it doesnt blow up the engine.

thanks,
paul

 

Well to be on the safe side you might want to check up on the cat after some hard runs to see if it is glowing. You dont want to burn out the cat and have it crumble clogging your exhaust.

 

Umm if you don't have that hose going to the cat then he doesn;t have the 5/6th ports working. They take some of the back pressure in that tube and use it to open on the series 4's. I believe it takes about 3 psi to open them.

As for detonating. It's an NA so it's hard to detonate them. I've run Bonez downpipe and high flow cat with Corksports single cat back and never had any problems like that. To make the most of the new exhaust you might want to get it tuned but by itself it should be fine.

The NA's are pretty damn rugged.

 

Ive got the mods listed below - strait exhaust and street port - and I still have the stock ECU and fuel system. I still run 87 octane gas and havent had a single problem. Its already been said, but if you dont have the split air pipe running from the cat, then the aux ports aren't opening.