[Fastest H-Town Realtor]

Congrats on the turbo...Any "Tune inna box" is about enough to get you to a good shop to do a dyno-tune. Nothing more. Houston has at least 3 great LS-1/GM 6.0L tuners. Try one. The low speed issue may be the fact that it takes a turbo a few seconds to spool up. My opinion is that it takes the STS unit a little longer than a normal setup to spool because of the distance from header-turbo-intake. A search on that topic is a must read. The thrown light could be a multitude of simple items.My guess is that the MAF signal is out spec. The dyno-tune would fix the light and may add a few ponies down low.