Ok, this may look a little gimmicky... but I am not opposed to trying something just to see if it works... worst case scenario would be out the cost of the software and having to replace the ECU, right? It may not have ignition retard, but even if it can do just a bit of fuel adjustment, that'd be like the Apexi Neo, which I hear helps "a bit" on this forum, and "helps even more on turbo or boost enabled cars" on their website (Neo) ... so, a little fuel remapping/adjustment could provide a decent benefit for the price: $100 bucks in this case, and you need to buy a cord to connect your laptop to the OBD-II port. Good thing is, this software seems universal. If you look at the supported options, some cars list a select few tuning options; I'm not sure if the Chevy/GM cars have all those AND more (i.e.-selected few options for some cars are less a few tuning options for all others not specified) or if the Chevy/GM options are more basic, like fuel mapping only, and DO NOT include the other options listed... for a bill, might be worth checking out. I have been enjoying the DIY approach; also, this comes with unlimited, novice friendly customer support on top of directions for use... What do ya'll think?
TOTAL OBD and ECU Auto Diagnostic Software | OBD-2 Reader & Scanner