i have a 400ex and i was wondering how much hp you could get from a slip on big gun exhaust and a k&n filter with a outerwear??

 

MY BUDDY JUST PUT ON A BIG GUN PIPE AND A #155
JET AND IT MADE A BIG DIFFERCE, I PUT ON A SUPER TRAPP PIPE WITH THE DYNO JET KIT AND K/N FILTER WE HAVE DIFFERNT TIRE SIZES ON SO I REALLY COULDNT TELL YOU WHICH ONE IS BETTER. THE BIG GUN IS PRETTY LOUD AND THE SUPER TRAPP IS QUITER. WELL I GUSES THE BIG GUN PROBLEY GIVES YOU MORE POWER THE PRICE IS ABOUT $200 SHOP AROUND
THE SIZE OF THE JETTING DEPENDS ON ELAVATION
WE ARE AT SEA LEVEL TO 1000 FEET IN OHIO

 

10% is a rule of thumb for full exhaust. 3-4 HP, with air box, good jetting, top line header silencer maybe 7-8 HP. I am looking at the FMF core IV squared. They are well known in the performance arena more so than recent up starts like Big Gun. But the head pipe is the important part of power. Instead of a slip on I would modify the stock unit by removing the silencer core and jetting, air lid. That is the same as slip on without the expense of the can.

 

hey there ex , i had the big gun complete system and i thought i was great, it had more power everywhere through the throttle. if i were you i would go with the head pipe also, the best price i have seen on the big gun complete system is 327.00 , from rocky mountain atv . i will give you a little tip , go to graydon prolines website and look at there 400ex complete system, i just ordered it last week , they claim it outperforms the gun by a little margin . when i had my big gun i was running a 165 pilot jet with k&n and my air box had about 10 1 inch holew in it, it was a ghood combination for me.

 

i forgot to tell ya, thay graydon full system sells for 275.00 , a great price...............