LS2 Pontiac GTO

Whats the difference between the two? I believe the E38 was on 05 LS2 GTO's and the E40 on the 06 GTO's.

gameover

e38 is the later PCM. E40 uses a CPU32 based main cpu and the E38 uses PowerPC.

LS2 Pontiac GTO

So basically just a software and hardware change?

ringram

Means code for the PCM is based on a totally different CPU instruction set. Like English and Russian. Means the tuning software programmers have their work cut out for them to write custom OS's for these 2 different PCM's.

I imagine that the calibrations for tables between the two were very similar though. Just the code that reads the tables will be quite different. Not sure on performance differences. Someone in the know might be able to inform us of that.

gameover

from a CPU perspecitve the PPC supports floating point, whereas the CPU32 doesn't.

Floating point values have started to creep into some areas of the calibration, but i expect over time more and more will be floating point. It's so much simpler without any need for internal scaling factors for binary precision. Really depends how committed GM are to cpu's with native floating point capabilities, and in this day and age not a whole lot of reasons why they wouldn't.

one thing's for sure - assembly for PPC is not as easy to read as CPU32 and also depending on the compiler chosen and compiler adherence to various "standards and traditions" in the computing world, PPC can be a real bitch in assembly. Anyway we have to worry about that not you guys

Chris...