I had a set of Hooker headers I had on my Bronco (5.8 V8) and they didn't bolt up right to the exhaust.... so I spent a couple days running around with just headers.... pros: LOUD!!!, sounds cool at idle, gets everyones attention.... cons: I was about ready to pass out from exhaust in cab, gets VERY annoying on the highway, loss of power, killed MPG's, and would have eventually burnt up the valves.... moral of story; you need back-pressure for optimum performance and best gas mileage.... IMO stick with what you got till you get that 40 series on there, I have the 40 on my bronco and i love it!