Give this guy a call his name is brent linderman (arctic edge motorsports) if u want sum good ideas...1-403-564-4673
I have this setup on my wife's M8 with an SLP pipeset (had the pipe first). The thicker base gasket provided raises port timing, and the head corrects the compression ratio. Pulls 2g heavier weights then previoussly, so it is making more power. No downside to this mod that I can see - the biggest "seat of the pants" difference is in the mid range and top end.
The 07-09 M8's were lacking in performance motor wise - the kit is a decent bang for your buck. My wifey's M8 has a 2.5 camo extreme 162", and clutching done. I honestly think any gain in traction with the 2.5 would have been wasted without the head/base gasket setup (loss of trackspeed). Very happy with it, no race fuel required. I am running a BD box, but improvements have been made to intake and exhaust as well - I imagine you can get away without one if you follow Kelsey's recommendations. Just be aware that you get what you ask for - a head designed for 6000' will require race fuel at lower elevations or colder temperatures.
If you ask ten people the same question, you'll get ten opinions, or "my buddy's sled" story. First off, most tuning issues I've ever seen with cut cylinder heads / big bores / etc is that they are bought over the counter at your local dealer or a specialty shop. Most (NOT ALL) dealers order a cylinder head package that is 14.1 or 14.5:1, as that is what the majority of thier customers want, so this is what they stock. If you order your kit from Kelsey, BE HONEST, and know your riding elevation, and if any other modifications are done, or plan to be done. I personally have never had a CR of more then 13.8:1 on any sled, as my primary reason for running an aftermarket head is better cooling (RK Tek stuff has never heat soaked on me, even on multiple runs up a hill). The "15hp kit for the M8 consists of a thicker (much thicker) base gasket to raise port timing (poor man's porting,this isn't a new thing, stacked gaskets and rave gaskets on 670's for years), and provide a tighter head to ensure correct compression ratio. Now, before you decide to order a thicker base gasket and plane your head at a machine shop, be aware that RK Tek has put a lot of time into knowing the proper amount of squish, shape of the combustion chamber,volume etc, etc. I used to measure deck height back in the day due to engine varience - they sure weren't identical. IMO, money well spent. If you buy it over the counter and expect y-pipe "A" to work with head "D", to work with pipe "F", you will be in for a tuning nightmare, or possibly a sled that is slower then a stocker. Spend $5 in long distance and call him, ask HIS recommendations. Hope this helps, PM me if you have any questions.
