I"m having a hard time following this.
You bought your bike in 2008 and from day one it "ran like crap"?
The dealer "fixed" it with YOU paying for the "fix" (never mind that it was never "fixed" to your liking).
Fast forward 4 years and you are looking at throwing more money for a tuner, heads, whatever.
If it were me, I'd find another dealer. There is something not right with your bike, they all don't "run like crap".
Now, if I'm off base, let me know. On the other hand, depending on your wishes, you can pull the motor, do the heads, whatever you wish. It's YOUR bike.
Me, I'm the type who will dig as deep as I must to find out the "why" and "how come" the bike "runs like crap"!
BUT, that's just ME!