i just recently took out my cat, and noticed a big difference. ow much HP do you think i gained? I also put an open element on my car at the same time so i am not sure what gave me the bigger increase in power?

 

My guess, probably not much. I've got a 91 Formula that has a 305 TBI (soon to be replaced) and I put an open element air cleaner on it, JET chip and a Flow Pro muffler and I didn't notice much of a difference. Then again I was too embarrased to take it to the track so I don't have any hard evidence. But it was a lot louder under hood and out back! Maybe taking the cat off helped you more than what I did?