What 4-stroke pipe gives the mst HP to an ATV. I have heard the Big GUn give 7-8. IS this good?

 

well thats a good one do we care about noise output? if not id go with a dmc but thats one loud offenseive pipe if u want some good power and you don't want everybody on the block to come to your house while your asleep and lintch you hehe look into a super trap or fmf powercore 5 or maybe the white bro E series

 

for a four stroke as of right now you cant beat the CT RACING system it was voted the most power gain for the 400ex in the dirtwheels 400ex pipe shoot out, however it was also the loudest of all the pipes tested. the quietest pipe you can buy that will give a good power gain to you 400 would be a FmF Powercore 4Q, but the best value for power, noise, and weight savings is easily the White-bros E-Series pro meg muffler.