2008 M1000 mods
look at the sticky for the M-series popular threads. You'll find helpful info.
1) If you're planning on running just an exhaust you cant go wrong with the SLP set up. You will need a fuel controller to run the pipe. I would also run a head & reeds and an EGT gauge to keep an eye on things. It will be a solid, reliable sled and run 91/93 oct fuel.
2) It is my opinion that the geared reverse DD on the 08s is unreliable. I run a Black Diamond Xtreme Diamond Lite Drive to get rid of the geared reverse. It sheds a few pounds. I had my ECU flashed to the 09 map so I could run the wires and have electronic reverse like the 09-up M1000s. Here is write up of how to do it
http://www.snowest.com/forum/showthread.php?t=230476
3) M1000s are heavy. The exhaust & DD drive upgrades sheds some decent wieght but i recommend a light weight hood & headlight delete. Big weight savings. Mountain Fit Hoods sells an awesome hood and an even cooler headlight delete kit that swaps in small 55w driving lights so you still have light. A gauge lifter is a good idea as well.
I love my M1000. Its a fantastic sled and the motor is excellent. Good luck!