this is a graph from factory pro's website showing the increase in power in the upper rpm range from their v-stacks (in red) vs stock (in blue)
Either way, they come with 4 stacks each. the question is after trying out both setups is, if you like the 2 stack setup better, can you sell the other 2 to someone else? And for what its worth, Graves Motorsports preps the factory Yamaha R6's in the supersport class so I'd like to think that they know what they are talking about since an R6 finished in first last year (yes, i know it had alot to do with the rider). I also realize alot more was done to those bikes than just v-stacks.
I have seen good dyno results from other people using the Factory Pro, all 4.....but it's hard to argue what Graves is doing as well. I spoke to a rep at Graves and he said you won't get as smooth a power curve with using 4, just better top end power for people drag racing who never go below full throttle.
It would be nice if someone actually did a comparison of both, Graves and Factory Pro, and also using 2 then 4. Hell, it would probably be the same....haha :lmao
Redline.....I am seriously having a hard time deciding on which v stacks to go with :roll: , probably splitting hairs between the Factory Pro and Graves. Did the 2 give any more power thru midrange than the 4? Did the 4 give more top end power than the 2? I hate to ask such nip-picky questions, but this is driving my crazy! :screwy I need to make a decision and purchase before I end up taking a hostage :stab .....haha
you really cant go wrong with either brand, they are basically the same item, just have small differences for patent issues. i would go with the 2 stacks cause a smoother power curve is a better thing to have then that extra 1-2 HP at the top range of your bike. but thats just my .13 cents :cheers
2 or 4 both had good gains.........mostly up top. The midrange was helped a little also. Just the install of the v-stacks alone flattened the power curve out. After testing 2 for several runs and making some map changes, i installed 4. With 4 I ended up with basically the same results.......however, 4 v-stacks would only make consistently smooth curves when the engine and exhaust was pretty hot (reason why it works for drags)
With 2, i had more consistent runs starting from 160 degrees engine temp all the way up to 200 or so. This is like street/track temps so.......I stuck with 2.
I think it is a waste of time and money to try and tune the extra .5 horse out of running 4 stacks.....when 2 will give you the almost exact results with less time and money. (if you use only 2, you can sell the other 2)
I'd recommend Graves........only because that's the ones that i have personally dealt with, although i'm sure Factory's are just as good.