L31 crate 350 with stock TPI induction and Hooker shorties/y-pipe. The y-pipe is the standard Hooker cat-delete version that reduces to 2-1/2 outlet. Currently runs to a Dynomax 2-1/2 catback. Got a great deal on a Magnaflow 3-inch catback but now wondering if it's worth all the trouble to expand the y-pipe to 3 inches and figure out how to mate it with the Magnaflow. Will I really gain much of anything with a stock longblock L31 and stock TPI induction?

 

On an engine that makes less than 300 horsepower, I doubt if you'd see any increase. You might even lose some low end torque.

 

Yes I think you will, on that motor. Definitely worthwhile.

 

Yes do it, when I bough my TA it had a 350 with some crappy 882 heads and terrible summit headers and it still gained going from 2.5 to 3"

 

Definitely something you should do. A good exhaust can free up as much as 30hp over factory set up depending on your mods.

 

Thanks, appreciate the input. Unfortunately, the y-pipe is really a problem. Can't find anyone local that can/will modify output to 3-inch. They all want me to bring the car to them so they can modify it on the car. Won't modify off the car because they've had too many people complain about their parts not fitting. Problem with this is I can't install the Magnaflow before the y-pipe is modified. But I can't get the y-pipe modified without the Magnaflow installed. Catch 22. REALLY wish I would have gone with a different header/y-pipe combo, but it was for the 305 and figured that would be fine. I really didn't expect to do a 350 swap in this car.

 

If the exhaust you want to put on is slip-fit, sounds like something you can do yourself in the driveway. No need for "shop".

Rent a chop saw and a wire welder at the rental yard if you need it. Chop the bottleneck off, weld on a piece of 3" pipe, install exhaust, done.