I have an 85 Trans Am, 305 Lg4. I need to replace the intermediate pipe and since the rest of the exhaust is stock I want to simply replace it with a stock diameter pipe......I remember measuring under the car and I measured 2.5', but when I called a big exhaust parts supplier they told me that the lg4(non-high output) came with a 2.25' exhaust. I want to order this new pipe now but I am questioning my measurements.....Since the car is stored away from my home can someone please confirm what size pipe this car should have come stock with????

 

2" outlet manifolds with single 2 1/4" y-pipe
82-87 305 LG4 (VIN H)
88-92 305 L03 (VIN E)
82-83 305 Crossfire
90-92 305 LB9 w/o G92 axle (VIN F)

2 1/4" outlet manifolds with single 3" y-pipe
83-86 305 L69 (VIN G)
85-89 305 LB9 (VIN F)
88 350 L98 (VIN 8)
89 350 L98 w/o G92 axle (VIN 8)

2 1/4" outlet manifolds with dual 2 1/4" cats
89 350 L98 w/G92 axle (VIN 8)
90-92 350 L98 (VIN 8)
89 305 LB9 w/G92 Axle (VIN F)
90-92 305 LB9 w/G92 (Vin F)

IIRC, the OE intermediate pipe on my 85 LG4 was 2.25. The after market cat back I replaced it with was 2.5.

JamesC

 

Thanks man....That helps alot. I guess I'll have to drive over to the car and measure the old one before I order, just to be sure it hasn't been replaced with a larger one, like yours.