[78w72]

hi. i'm ready to purchase an exhaust system for my 72 firebird & am having trouble deciding which is the best way to go. looking at the pypes kits with dual mufflers but my dilema is do i get the 2.5" or 3"? so i'm looking for some input &/or pics of a 3" system on a early 2nd gen, or later years too. the engine could benefit from 3" & although its not a full time drag car i dont want to choke it out with 2.5". who is running 3" on their bird & what problems did you run into for clearance on the floor? i know the cross member can be an issue or the cross braces in the floor, & possibly the fitment of the tail pipes in the rear. the car is lower than stock but not excessive & the headers do hang a little lower than most due to their tube size.

i looked into doing a custom kit with 3" x pipe & 2.5" tail pipes but pypes doesnt make that easy if you want to order it that way, they make you pay full price via PY & charge shipping on top. yet summit & jegs has super low prices for the standard kits but pypes wont let them order just rear tailpipes. you'd think they would offer the custom kits for guys with higher hp engines or be somewhat competitive on the prices with the larger retailers they sell through, but apparently not. i am all for buying from PY but just cant justify $100 more compared to summit when on a tight budget. so its looking like if i want to have the better flowing exhaust for my car i need to buy the 3" kit, or piece it together to get the 2.5" tails & spend ~ $100 more.

engine dynoed at almost 520 hp with no tuning yet & i have plans for more power in the near future. pretty sure 2.5" will not be enough for this engine. pics & opinions would be a huge help...

400/467
stock e-heads
old faithfull roller cam
SD ported cast iron intake & cliff prepped q-jet
hooker s/c 2" headers
th-400 trans.