Hey everyone,
I have a 1990, F150, 302, all stock. I have several questions regarding getting a new exhaust system for it.

1. By just changing the muffler will I see a difference as far as the engine running more efficient (more HP, better gas mileage) or will the change be just to get a different sound?

2. If I do change the muffler will I have to also increase my pipes from the catalytic back (they are currently 2 1/4, I would just go to 2 1/2). Would increasing the pipe size give me more performance or just increase the sound?

3. Also which muffler has better flow, Flowmaster or Magnaflow?

I have spoken to both companies and different exhaust shops and I've received many different opinions about increasing the pipe size. Some say that it will just increase my sound but not give me much more improvement if I was just to change the muffler since the pipes from the headers to the Cat is still 2 1/4.
Basically what I'm looking to find out is if should just save my money on increasing the pipes and just do the muffler if there is not going to be a significant change. I'm looking to make my engine run more efficient (better gas mileage, more HP) sound is secondary to me,

Thanks for any help!

 

I'd go Magnaflow. Don't increase pipe size too much or you'll hurt your torque a lot. Magnaflow has all these answers on their website as well.