3 port = more low end torque, good for short, small, tight and alots of turns (parking lot layout) track....
5 port = more high end HP, good for large....etc complete opposite to 3 ports.

However, that doesn't mean 3 port does not have top speed, or 5 ports has no low-end torque....no engines are perfect, just they are better on 1 thing then the other.

OS 12 TZ is a good sub $200 enigne...at least, the parts support is a little better then SIRIO.