Questions about hooking up RB streetable header to gutted out cat
 

Hey guys. I drive a stock 90 vert. Im looking to buy the RB streetable header. I already have the RB dual catback. My only question is that if i gut the cat in between the y-pipe and my RB header. Will the back pressure still be suficiant enough for the 6pi? Any help is appriciated.

btw i dont want to get that RB presilencer...
 

I think its a waste of money. But would it be to loud with gutted cat and the setup i've described or not have enough pressure for 6pi? If so then if i dont gut the cat will it still be louder than stock and have enough pressure for 6pi???

If you have an s5 it doesn't matter. The aux ports and VDI are controlled by the air pump and two solenoid valves.

It will be very loud, and you'll have to extend the header to get it to bolt up to the gutted cat. The header is meant to be used with the RB presilencer, which is about 3" longer than the stock main cat. You'll end up with a 3" gap that will need to be filled somehow. And yes, even if you don't gut the cat, it will still be louder than with the stock exhaust manifold. But it would obviously be quieter than with the cat gutted.

6PI and VDI are unrelated as arghx pointed out.

one more question guys
 

I just found a stainless steel pacesetter header. Will there still be a gap between the header and the cat or is this long enought?

the Rx-7 pacesetter headers are not highly regarded for quality and longevity.

ok
 

I have heard that. So if I get the RB header and no presilencer can an exhaust shop just weld a short double flang pipe?

Yes, or you have the end of the header cut, then a ~3" piece of 2.5" tubing welded in. Measure the exact distance before assuming it's 3".

+1. '89-91 is S5, so you're golden. As long as you keep the air pump your 6pi will work, since your car uses air pump pressure not exhaust pressure. The exhaust doesn't matter in your case.

As for the header I'd read the text on the Racing Beat website. Their downpipe is cheaper, makes about the same power unless you get a carb, and if I understand correctly doesn't make the noise that headers do. That's b/c most of the power gain comes from removing the cat. So really if you're going to gut it or replace it with a pipe you don't need to buy anything. Though a high performance cat is affordable enough that I'd just get that. And a pipe is of course louder than a pre-silencer or cat.

Dont mean to question anybody but isnt the streetabale header also the collected header? Because then you will not need to modify it to bolt up to the stock cat. It has a single outlet that bolts up like stock vs the dual outlet true dual header that would def need to be modified to bolt up to the stock cat.

^ Yes, it is the collected header, but that's not the issue. As I mentioned before...

Also, the RB downpipe will suffer from the same gap if used with a stock cat or something the same length (~17" long).

you can get the header and cat package from RX7.com, its the RB header and a Hi-flow cat (emissions legal cat too) that requires no modification to bolt up to the stock exhaust, its $440, which is a good deal because the cat alone is $250 which makes the header $190.