ok I have not found any threads on this "specific" situation and need some advice.
If I am stock and then I removed my cat and added a VX muffler connected by 3in piping with single piping back from the stock Y, would I lose low end torque?

I feel like I have lost some.

How can I get that back? Will a 2.5 in pipe back to a magnaflow help? Now sure what to do.

 

If you lose any, it shouldn't be noticeable. You should actually pick up a bit of power, as the flow is less restrictive.

 

That is what I thought too. Do you think there is a pressure issue with 3in piping instead of 2.5 with a stock engine setup?

 

3" piping for a stock motor is overkill. Best to run 2 1/4 - 2 1/2.

And yes, it has been rumored here that removing the cat when it is NOT clogged can result in low end loss. How much?? Who knows.

IMO, its best to run a high flow cat with 2 1/2 piping (max) to whichever muffler you choose. Then exit the exhaust wherever you like.

 

3" single, or 2.5/2.25 duals should be great for these motors. Of course, then the heads become the major choke point.

 

i definitely felt more hories in the 3000+ range. i really want more low end tho and i never go over 2000 rpms. any suggestions. thk i should do 2.5 back to the muffler then 2.5 out?

 

I had 3" pipe on my firebird, and it was a Torque MONSTER. I attribute a bunch of that to the TPI intake though......

 

Currently I run 2 1/2" duals without cat, it actually brought my power band lower in the RPM range.

 

2.5 in duals are pretty much the maximum for a stock 318/360, me thinks.