LRP 28 S3 has decent RPM's and plenty of power for a truggy. $170. You could go 30 S4/32 S4 as well, but while adding power, probably losing RPM's and fuel economy.
I've had 4 or 5 28 Spec 3's and I think my 30 in my savage is a spec 2. Not sure what the "spec 4"'s have that mine don't...