I will give the pressure chamber in the pressure line a try.
Side exhaust engines in this car are awsome, I sometimes run a K.12 RB in the car & it flies with no issues on tuning at all. I won our winter nationals with the side exhaust NTC3 earlier this year, in the pullstart class. At our state titles in April I was having so much trouble with the engine I bolted in the K12 as well, it was competitive in the tight sections but off the mark in the fast sections. The track is huge though, it is the track they ran the 1/8 scale worlds in 2001.