GreenMachineButler
New member
So I posted this in the new users thread a couple days ago but I wanted to post here since my account is active now. I have a 2015 sonic rs and I have read about the power output dipping at around 5500 rpm and mine doesn’t so I was wondering why that might be because I just bought this car, I found the original owner of the vehicle and he told me when it had only 5000 miles on it the radiator cap failed and caused it to blow a head gasket, when he had the gasket replaced he had stiffer valve springs installed and he also had the shop port and polish the head before reinstalling so I think that explains why it doesn’t have that dip in power, it also had the gm performance exhaust installed with the calibration from the original dealer, I also noticed that it doesn’t hit the rev limiter until around 6700rpm which I just noticed last night while testing to see where the rev limiter kicked in, there doesn’t seem to be any valve float or knocking at that high rpm so I think the original owner was telling the truth about the stiffer valve springs, my question is would I benefit from a wide band o2 sensor before contacting bnr for a tune? I’m sure the boost pressure is different from stock due to the head being ported and polished, and also can you do multiple preloaded tunes with bnr because I would like to have a performance 91 octane tune, a 100 octane tune because I just found a station that sells 100 octane at the pump really close to where I live and an economy 91 octane tune, of course I would want the 100 octane tune to be an all out performance tune that I use for kind of a “fun” tank of gas at the track
