Best year motors?

[250Renvy]

For my Hybrid, I've decided to go with a 2007 CRF 450X motor. I'm getting rid of a 2005 CRF 450R motor with some head porting and valves etc.

I keep hearing that honda and yamaha have toned down their bike motors over the years. So where do I get the right information on what the best year motors to run are?

Am I really going to notice the difference and will a few simple mods make up the difference?

I really want something that is new considering the whole quad will be built from new parts. The only thing that will be used is the 250R motor (Yeah baby - dual mounting system)

[TheNewn]

I dont think the year differences will be horribly noticeable, but they are there. And if i remember right i think the 2003? or 2004 motors are the faster ones. Nothing a few bolt ons wont catch up to and probably pass.

Why not just buy a TRX450R motor instead of a CRF450X? Pretty much the same.