ok i have RB headers and i wanna order RB presilencer but i would like to know the length on the presilencer and will it bolt up to my 3in catback i have an s4 non turbo any info willl help

 

Stateing the obvious, you'll need to swap out the flange on your cat back to 2 1/2 inch since the NA Presilencer is 2 1/2 inch. The RB headers are already 2 1/2 inch.

 

but its an aftermarket catback JIC exhaust .. damn this sucks lol

 

what if u cut off the flange on the RB pipe and weld a 3 inch flange on?

 

Thar works too, just got to decide which one to save and which one to hack up.

 

^ agreed

 

In truth, I'd not hack the RB presilencer as it is a more replacable item than the cat back and it's already married to a RB header. For instance, what if you came across a killer deal on a RB Cat Back???

 

If you can stuff a 2-1/2" to 3" adapter in between (may take some ingenuity) that'll work and you won't have to hack anything up. Might take some persuasion of the hangers on the JIC exhaust, but it'll work.

 

so once i remove the flange from aftermarket cat and weld the 3in flange onto cat and connect to catback and make my pipe from header to aftermarket cat .should work

 

you should have gotten 2.5 in cat back... much better for non turbos but oh well...

 

+1 Too much back pressure reduction in an NA isn't good.

 

^^ agree

 

Is the JIC cat back currently installed on the car with the stock cat?
Is the RB silencer designed to bolt up to the stock RX-7 cat back?

If both of those are yes, then you should be able to bolt the presilencer to the JIC with no modifications necessary to either. It may not flow the best... but you aren't hacking up parts either.

 

Jic catback is 3 in.

 

^^ yes JIC is 3in