RB Header and main cat?
 

I know the RB street header won't bolt-up to the stock exhaust system as such.
I'm wanting to use the header with a replacement main cat, which I already have, and then a normal dual exhaust.
What's the reason the cat won't bolt-up in place? Is the RB pre-silencer that takes the place of the cat in the RB system too long/short? Is the header longer than the stock manifold and pre-cats?
In other words, would I have to have a section of my existing pipe cut out or a piece fabricated? There must be a common work-around that I haven't thought noticed. Or is everyone who's running the RB header just ditching all the cats?

Thanks,

CW

I believe most people are buying either the header and pre-silencer OR header and bonez free-flow cat combo. Both of which bolt striaght in. Personally, I wasn't a fan of the RB pre-silencer! You can read about that in my other post. The difference in horsepower between the free-flow cat and pre-silencer is minute and exhaust tone is almost identical.
The reason the stock cat doesn't fit into the mix with the header is because its too SHORT (approx. 17 5/8"), while the free-flow cat and/or pre-silencer replacement measures approximently 20 3/4".
If you want to use the stock cat with an aftermarket header as a bolt in without modifying your current exhaust system simply cut off two of the flanges from your pre-cats(since you'll be removing these anyways), and have them welded together to make the extension (make sure you measure, cut, and weld as straight and presice as you can). This will allow you to use any "stock" cat replacement with the addition of an extra exhaust gasket.
I had mine setup like this for awhile while I was experimenting with different setups, if you want that deep tone, the stock cat really keeps the exhaust tone down.

Thanks Soma.