How much flow do you need? depending on the size pipe hes planning on running it may be overkill. Unless hes running some kind of forced induction the stock pipes with a replaced muffler will be fine.

Stock duals are 2.25 passed the muffler

 

I probably should have been clearer. With an x-pipe, the flow advantage gained isn't really from just volume. Of course that will depend on pipe sizing, etc. An x-pipe balances the flow characteristics of the system. IMO, that muffler would act more as an h-pipe which is used more to balance pressure.

 

what is the diameter of the stock exhaust and what size muffler do ineed inlet?

 

6" digital caliper...$10 HERE

 

lol, 3" in dual 2.25" out

 

Mopowar i sent you a private message.
2.25 after muffler ok. what about before?

 

the magnaflow is a "tru-flow x" so chances are it looks like this on the inside
http://store.summitracing.com/largei...52_cutaway.jpg

 

Are you still asking what size befor the muffler?

 

Usually you would want to downsize as you go through the system. The idea is that as the exhaust gas cools it contracts, so you want the pipe to accomodate that contracton in order to maintain velocity. Many performance shops use a laser thermometer to try and ascertain where to downsize. Old school they would just note the discoloration of the pipe. All this is academic though without a good set of headers to start with. If it was me, I would just put something on there now that sounds good and wait for someone to develop a good set of long tubes before I dropped a bunch of cash into the exhaust. Without the headers, the gains will be minimal anyway.

The worst thing about owning a new vehicle is waiting the aftermarket to catch up.

 

I have to agree, that dumping a bunch of cash into it now may be pointless. Either just swap the muffler or wait until you can build a full setup from headers back.