What is the overall diameter of the stock factory y-pipe on a 1991 305 TBI engine. Also who makes a larger more free flowing aftermarket y-pipe and what size is it? Is the factory y-pipe on 305/350 TPI engine with single cat the same size as the 305 TBI y-pipe?

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Turbo Bob

 

the stock ypipe is 2.25" at the wide spots about 1.75" in the turns. i used an slp ypipe for a while that i was very happy with. if you get the ypipe that is intentended for a 3" cat and get a high flow cat at the same time you can expect a noticable gain in top end power and the exhaust note will come to life.

lata
tim

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91 Camaro RS-LO3,Auto.
14.301 @ 94.39mph
The car is going street strip for next season. 13's here i come!!!!!
Edlebrock TES Headers, Cat Eliminator Pipe, Borla Adjustable Cat Back,Marche Pulleys, HyperTech Chip,Transgo Shift Kit,B&M Convertor(2000stall),Steve Spohn Rear Rig( all rod ends), Poly Front Bushings,Ported TB, 350 Injectors, Edlebrock Performer TBI Intake, Performer Heads, 1.6 Roller Tipped Rockers
http://www.mycar.net/mafb/registry/detail.cfm?id=299

 

I dont think you'll find any company that makes a replacement y-pipe for a stock TBI. You'll need to get headers with a y-pipe, or have a muffler shop make you a custom mandrel-bent y-pipe. A TPI y-pipe will not bolt up without modification because the exhaust manifolds are different.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

 

SLP offers such a pipe but headers would really make a difference.

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Mongoose-NCTGA-1990 Pontiac Formula/305 TBI-700R4 with Edelbrock Performer TBI intake,TES headers,and STB,K&N,MSD-6AL,Holley laser shot coil,Accel Extreme 9000 wires,Jet Stage 2 chip,TCI shift kit with corvette servo,Richmond 3.73 gear with Auburn 3 series posi,no cat,SLP 3" cat back,Eibach sportline springs,Energy Suspension poly throughout,Lakewood LCA and adjustable panhard bar package,SSM subframe connectors,IROC wonder bar,Tokico 5 way adjustable struts and shocks,Autometer electric fuel pressure gauge,Alpine,JL Audio,MB Quart,92 GTA taillights,92 GTA aero wing and hatch,Steve Spohn LCA relocater kit,MacEwen White face gauges,84 T/A cold air induction air cleaner,Grant Formula GT wheel.