I'm deciding over the flowmaster 40 series or a magnaflow. A friend also told me since i only have a 2.5L that it would sound dumb with one on. is that true? or will it sound good?
This won't sound good at all. I have owned 3 jeeps in the past. I put a Flowmaster 40 series on my first jeep, a '94 Wrangler 4.0. About a week after I put it on, I decided to reinstall the stock exhaust. It made my Jeep feel like a dog with a bigger bark than bite. The only times I have ever heard a loud aftermarket exhaust sound good on a jeep was when it had a V8 and was beefy enough to match its roar. Your 2.5L just doesn't have enough butt in its britches to pull off an aftermarket exhaust. I would recommend using the money towards more practical accessories like bumpers, lift and tires, tops, lights etc. You can get some great ideas from Jeep blogs and catalogs. My personal favorite sources for inspiration are Quadratec, JC Whitney, and 4wd catalogs. Just look at some other jeeps and find what you like and what satisfies your needs/wants.