Okay on a modded 5 port it's going to be hard to tame. That engine had power the way it came,IMO. I owned [blew it to hell] a rb modded 5 port that really belonged in a truggy or stripped out geo metro! I used a dynamite 086 with that engine until I got the go-tec 2072. The 2072 will smooth it out,but for some reason even tho the dynamite 086 makes it a handful, you can tame it down with clutch springs. I used some kyosho .95's. The 086 pipe gave me close to 13 min run times as where the 2072 dropped by about 30-45 seconds. I am not a super talented driver so for me I lucked out and was able to pick up a modded 3 port which I really like. But for the ultimate engine, smooth,power up the a$$ I run an mg-66 with the 2072 pipe. run times 12:30's. So if you don't have either of the pipes I would rec. the 2072. The pipe can be found at answer rc usa which is the usa distributor for massive mods mg-66 http://www.answer-rcusa.com/