How restrictive is stock 97-04 regal gs exhaust?

[deezdad]

Looking to run a 3.5 or 3.4 pulley gonna go with front & rear plogs with equalizer crossover/downpipe but that's where I have a question.. down pipe comes with 2.5 exit for stock size exhaust OR 3" exit for 3" exhaust.. is 2.5 adequate in this case or is 3" necessary?

 

[T-CHRGD]

I have an LS, with a 2 1/2" downpipe and stock exhaust. The downpipe alone (eliminating the "U" bend) works great. With a GS, I would probably go 3" with 3" exhaust.
Another must have mod is the "F" body 12" front brakes. I've had them on all 3 of my Regals (GS & LS). They are a great match to the factory 11" rear discs.

 

[deezdad]

Awesome thanks for the tip.. ended up getting 3" dp & exhaust along with a short stack intercooler they say the equalizer crossover about runs into the tbody so the ic gives it a little clearance.. you've said in the past zzp coilovers didn't work out too well I'm considering the lowering ready struts they sell.