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Discussion Starter #1
Does anybody know if a big gun rev box and a big gun slip on exhaust with no jet kit will add any power and if also will it add alot of enough power to notice? about how much hp will be added?
 

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I couldn't tell you a hp number, but NO. You should take your air lid off and use it as a coaster. You need to jet for the exhaust. Even tho its only a slip you should jet for it. You might get a little performance but mainly noise. The rev box is nice but hard on your stock valve train. They suggest new stiffer springs and even valves, I myself am running stock valve train, but plan to upgrade soon. You just have to make sure your not always banging the topend when riding
 

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It allows the motor to rev higher and changes the timing curve slightly. In one of the other two posts that you were asking the same question I brought up upgraded valve springs. If you rev that motor too high for too long your valves will start to wander a bit and you could have catostrophic failure.
My answer to you would be that since you are obviously either too cheap or too scared to just re-jet your quad you sure won't be able to open it up and install new valve springs. If you run it too hard you'll really regret it.

Get a full exhaust a better flowing filter/intake and re-jet it.
 

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:bash: Its not giving you horsepower. Horsepower cost alot more than $100. It opens up your rev range, allows you to rev higher than factory. It also changes when you "Spark" for a more thourogh burn. Its not a fuel injected bike so its not like a programmer in truck. I Have a procom only because I have the full intent of opening my motor this winter, Spize909 is probably in the same boat, he dosn't want it to do damage BUT if it does he/I am prepared to get into my motor. Its called "supporting mods". If I change the speed at which my valves are designed to work at, I need to do the supporting mod to my valves to insure there reliability. If I do a BBK i need to give it more air/fuel ie...FCR39, a supporting mod. If I do that then I need to give that air some where to go so here comes exhaust. It all ties together in one way or another.

A few months back me and another member Barncat were running side by side on pavement, we had about a 3mi stretch to run. He was on a DVX with nearly the same mods as I have except I have a rev box. I always carry my stock with me so I put it in. 1st run 5th gear pinned we were dead even for all 3mi. 2nd run I switched to the procom the extra 1000rpm kept me a good 10-12ft ahead.

If I had to say anything about the revbox, it would be that I feel it makes it more explosive. When am coming out of a turn or slide, if just explodes thats the tweak in timing not added hp.

To answer your other posts right here. Dont waste your time with a slipon unless you are just wanting to be louder or a poser. Looking at the factory headpipe it comes out of the motor down a little then to the left then down and blah blah blah. My Curtis sparks pipe is a larger diameter, and a straight shot,it comes out of the head and immediatly sweeps to the back straight. Research with the search button on here or any other forum about exhaust and wil hear the same thing. We don't just say cause we are mod snobs it has been said and proved on dynos for years...IMO:D
 

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Discussion Starter #11
thanks this helped alot im going to get the rev box because it seems like in your post to work good and im also going to get a big gun slip on because i dont really need a ton of power added u just want enough so when i come out of a turn in 3rd gear it revs somewhat quicker and pulls a little bit better
 

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A big waste of time and typing................and no I will not have to open my motor up. I have KW springs (and valves) in it already and before that DRZe springs to go along with my rev box.

Cameron you will feel a difference if it's even just a little the sound will make it feel like more. Just do not hold the high rpms for too long.........remember this warning.
 

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A big waste of time and typing................and no I will not have to open my motor up. I have KW springs (and valves) in it already and before that DRZe springs to go along with my rev box.

Cameron you will feel a difference if it's even just a little the sound will make it feel like more. Just do not hold the high rpms for too long.........remember this warning.
I had forgot that you had KW's....Big waste of time but I was bored, home with a sick kid watchin the news.....
 

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Discussion Starter #15
do either of you know what the stock rpm is for the kfx 400 is at rev limiter and maybe how much rpm the big gun rev box actually adds
 
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