All 5 engines avail in the Go range ie 3 5 7 port .21 and 6 port .25 , .28 are great for truggy.

in my experience the 3 port R Spec has a rally feel if you like blipping the throttle.

5 port is a bit of a stump puller

7 port is a little more linear with a tad more top end

Advantage with .21 is tank time and not over powering the drive , less stress on the drive train .

25 and 28 are just brutal and maybe too much IMO

Advantage with .25 and .28 .... Um ... GRUUUNT ! lol
and ... MORE GRUNTT !!

M