the 3 port engine i run is a (novarossi, .21bf) its about $150 and the (dynomite 86 pipe i got was $50.) i would just run the (stock engine) you have now intil it needs to be (rebulid, so you learn how to tune a engine etc.)
novarossi holds a tune really good and, not to hard to tune,but if you ever have a leak on a engine you, wont be able to tune no matter what you do.