I got a buddy with a Raptor 700, who is looking to stroke it 5mm's. What rod length, and pistons does he need? Also, does the combustion chamber need to be machined 2.5mm to fit the new crank? I'm guessing it does, to clear the piston and to get the squish right. But, he thinks the hotrods +5 crank is a direct drop-in, with no modifications. Any Rappy guys out there that could help me out? Thanks.