ok i just put on some dynomax shorty headers, and my muffler shop said he would run dual 2 1/4 all the way back (in the stock location)no cats, with mufflers and everything welded for $200 is it worth it? would dual 2 1/2 be a better idea for the car in sig? i just want something that sounds nice and i thought this would be a good idea.besides otherwise i would have to get a custom Y-pipe made so why not go all out..

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87 IROC-z 305 TPI
Borg Warner T-5 fresh rebuild
10-bolt 3.73 Richmond gears rebuilt GM posi,
formerly BW 9-bolt w/3.45 gears(broke it)
Ported Plenum and Runners Homemade AFPR
ACCEL 8.8 wires, High output coil,and cap & rotor
Bosch platinum + 4 plugs
Ram Air w/ K&N filters,
MAF sensor screens removed, TB coolant bypass
Polyurethane tranny and torque arm mounts
Gutted Cat, Dynomax Headers & catback w/custom tips
K&N oil filter,Mobil 1 synth,Factory Oil Cooler, Futura GLS Super Sport tires 265/50/15 rear and 235/60/15 front mounted on 86 monte carlo SS rims.

406 siamesed TPI in progress

 

You should run 2 1/2" IMO. With a 305, it seems like you have a pretty narrow window: you might as well do a single exhaust instead of 2 1/4" duals and I've been told by a lot of people that 2 1/2" is as big as I would want to go unless my engine is seriously modded, which it isn't.

 

dual 2.25" exaust has no advantage over a 3" exaust for anything other than sound. Will the bends be crimped? If so, the cross sectional area will be even smaller.

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-Tas
'89 Formula WS-6

305, TBI, 700R4, P.A.W. 14x3 open element with K&N, Milodon 160* thermo, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips, Hooker 1-5/8" 50 state legal headers, Dynomax 3" I pipe (PN 44063 and 43248)
Super GRK_Taz World
F-Body Dual Exaust
EFI & Intake Options

 

i decided to just get my Y-pipe modified, it cost me $50 and the only part that he used was the part the goes into the cat, so basically he made me one, I removed the cat completely for a straight pipe, and i basically decided that i should wait til i get some really good headers(SLP) and have the 406 done before i put some money into an exhaust, oh and btw he does mandrel bends, but like i said i know the guy and he gives me real good deals.

and i am really happy with the sound of the car, its got a real sweet rumble, one thing i might do is replace the dynomax muffler with something louder, any ideas? its got a single 2 1/2 inlet and dual 2 1/2 outlets.the pipes are all new so i want to reuse them. thanks guys

------------------
87 IROC-z 305 TPI
Borg Warner T-5 fresh rebuild
10-bolt 3.73 Richmond gears rebuilt GM posi,
formerly BW 9-bolt w/3.45 gears(broke it)
Ported Plenum and Runners Homemade AFPR
ACCEL 8.8 wires, High output coil,and cap & rotor
Bosch platinum + 4 plugs
Ram Air w/ K&N filters,
MAF sensor screens removed, TB coolant bypass
Polyurethane tranny and torque arm mounts
Gutted Cat, Dynomax Headers & catback w/custom tips
K&N oil filter,Mobil 1 synth,Factory Oil Cooler, Futura GLS Super Sport tires 265/50/15 rear and 235/60/15 front mounted on 86 monte carlo SS rims.

406 siamesed TPI in progress