So, I have intake, headers, exhaust on my 86 gsr, but no other performance mods. Everyone says the next step is a high flow cat. I guess I have 2 questions:

1: Does a high flow cat make you gain hp and torque? I heard it reduces horsepower cuz of loss of back pressure.

2: If a high flow cat increases horsepower, should I buy a carsound, or just go to a junkyard, buy an old cat off an integra, and gut it? Would THAT be too little back pressure?