[s346k]

i can contribute some info to this debate. anecdotal results but this is what happened.

full exhaust
stock lt2 manifold
stock tb

vs

full exhaust
stock msd
stock lt5 tb (ict billet adapter)

m6 car so i feel that is within the tolerance of driving & weather conditions, so its hard to say which one was realistically better. i measured 60-130 from hpt logs as this was before i had a dragy. 6 pulls with lt2 and 3 with msd. difference of averages was <.2 seconds. at that point the car was going 9.6-9.7. the msd was indeed faster but not by much. possible lt5 tb adapter issue.

if i had it to do over again i would have done a stock unported lt2 manifold and used a stock tb. having a larger tb than intake manifold is asking for tuning issues and a waste of time imho. achieve the same results with a pedal commander and never turn a wrench.

also. if using an lt5 tb, i suggest ovaling the mounting holes to avoid using any adapters. i was not happy with the ict billet adapter and ultimately took it off. the car kept showing low map kpa and i believe the adapter was contributing.

to answer your question: leave the tb unported. i saw .5 hp gain on the dyno from a ported tb on my bolt on engine.