Originally Posted by bnekic
Regarding the BMS piggyback,
You see things on the dyno graph that are "stressful and your not happy with" but your not a professional tuner?
Sorry, I am only paid to drive so I have to defer to what I have seen and this specific set of graphs posted by Terry@BMS is not as smooth as some of the cars I've driven but you can see even the stock ECU that he had was not ideal to work with and this isn't a limited edition car with each engine tuned from the factory.
Fuel has a 5-10% lean area at 3300-4200rpm vs BMW which seems to happen as HP levels out and then BMS gets rich on the torque dip regaining it's HP advantage over BMW, and then gets lean again at 5800-redline but this time it seems that BMW's tune is losing HP to BMS until some crazy engine change at 6200 giving BMW more torque and BMS less although I can only imagine this is a fluke though.
The next two graphs seem to be +3psi (bottom) compared to BMW (top graph), neither is very effective at keeping boost at X but skipping the last spike at the end, BMW's has the tighter/more controlled range.
Personally from a driving perspective the torque curve itself is very peaky in an area that I don't use which generates impressive peak numbers below 3000, but I shift closer to 7? so the 4500+ area is important to me and the gap is decreasing compared to BMW on top of Terry telling me it was 'meant more for street cars, drag cars, etc' when asked about road racing DE type events.
With all of that being said, one of these (probably BMS because they actually talked to me unlike some others) would be in my car right now if I didn't have to take it out every week that I wanted to do more than a 1/4mi run or a semi street legal sub 75mph punch up a freeway ramp but for these types of things, it's great.
Also, Terry@BMS said that even the stock car can benefit from some additional octane and his setup definitely would. I didn't get a clear answer so I don't know if those dyno plots were with 91 octane (the highest commonly available to CA residents such as BMS) or if it was an e85 blend or something along those lines.