I have 2 1/2 gallons on my GTR and it is a good motor, and have had the old style speed, and wouldn't even compare the 2. Don't get me wrong, its a good motor for the money, there's alot of new motors out now, and I've tried a few, and I'll leave it at that.
My motor set up was posted a few pages back, mine is set up for smooth linear power band, mad power doesn't mean much if you can't plant it. I also get better than average run times, theres a few here that were there when I ran a 12 minute main on the big track at Fear Farm on one tank.
I did pull the break in shim out after 1 gallon and am still running a P3 plug.
I will say the head does sit alittle lower than others and is lighter.

Don't take this the wrong way, I'm not knoking the motor, I've had good success with it,just giving an my opinion