I did the same as BBS, just for the he!! of it when i installed my HPD exhaust i started it up with just the header installed. IT WAS LOUD! Bottom end sucked it seemed slower then before. I only ran it for a min or so because any engine savvy guy would know without adequate back pressure the exhaust valves will cool down then be heated again causing them to crack.

If your looking for more power get an aftermarket exhaust system!

 

it will be fin my dad has a 04 srambler and he did it.it is not that loud it is loud when you accelerrate.

 

no u wont be fine. these ppl no what there talkin about. but heres my question, does the need for the back pressure change with more cylinders because all the motorcyles that i see and alot of cars and trucks run strait pipes. whats goin on here?

 

I ran straight drag pipes on my Harley for a short time. After I realized how much low end torque was lost, I put some baffles in it to increase the back pressure. That helped some, but not as much as when I have my pipes with mufflers on it. Some motors need the back pressure to run properly, while others can have less.