Will rnr downpipe + apexi ws = problems?

[kmartind]

I have an Apexi WS cat back (3"), which I bolted to the stock cat and downpipe with the neck-down adapter Apexi supplied.
With the neck-down removed for a 3" connection, it looks like the cat-back would be a couple of inches too short to connect to the stock cat location. BTW is this similar to the N1 exhaust? Does that mean the Apexi downpipe also extends a couple of inches past the stock cat location? I've haven't noticed this being discussed here, and a quick search didn't turn up anything.

Anyway, I'd like to run an O2 eliminator downpipe and high-flow cat. The only option I can think of that doesn't involve welding is to go with a 2.5" downpipe with 2.5" high-flow cat and leave the neck-down in place.

1. Am I correct in assuming that something like an rnr 2.5" O2 eliminator downpipe with high-flow cat will actually mate up correctly with the flange on the Apexi neck-down (which is designed to bolt to the stock cat), with just a new gasket?

2. Will there be a noticable performance impact going with 2.5" up to the cat-back vs 3"? (plan to upgrade to a "small" turbo like an FP Big28, at least for now)

3. Any better ideas? (keeping in mind that even without the neck down, the Apexi cat-back has a 3" flange, not slip fit).

 

[Green93TalonTSi]

Yes ull see performance gains with a 2.5" dp. I went with a 2.5" dp, 3" hi flow cat and the Apexi N1 catback. I just had a 3" adapter made that looks exactly like the 1 apexi supplies.

 

[RnR Racing]

Yes, our system will bolt up to that catback. We can also make a pipe that eliminates the adapter you have.