I do have / use HPT for my LS2 but I don't "tune" my engine for several reasons.
- My engine is stock and I've been told by multiple tuners with vast tons more experience than me that there is almost nothing to be gained on a stock LS2.
- I don't have access to a dyno.
- Without a dyno you're just shooting in the dark.
I am still glad that I own HPT though. I was able to disable VATS, torque management, disable DTC's, and all the other little things that are required to get the engine to run as a standalone without having to send anything out. I am also able to go back and and play with things over time without having to send the ECM somewhere and disable the rig. The diagnostic scanner is way more powerful than any other. I've also been able to get a hold of some "aftermarket" tunes from some reputable "tuners" and found that some of them are not really doing anything anyway. Some very obviously have no clue what they are doing.
Just my opinion but if you are going to send your ECM out for a tune and have any aftermarket power adders you need to make sure to send it to a place that OWNS a dyno and has done HUNDREDS of tunes. The only way to get anything relatively in the ballpark will be to get someone who has done hundreds of engines with the same / similar mods. Enough to where they know they can get you in the ballpark without running you on the dyno. Even then you're leaving some power on the table because every engine is different. Without that kind of experience you're just going to get a generic BS tune that is ...
- ... a copy of some high performance stock tune. (IE, they will erase your stock info and paste a tune from a Corvette, Cadillac, or something else in its place.)
- ... a terrible tune that will damage your engine.
- ... a terrible tune that will leave tons of power on the table.
If you have a stock engine and send your ECM out you are probably going to receive something with VATS disabled, a generic listing of DTC's disabled, maybe a cut and paste OEM tune, and random bits and pieces of torque management disabled.
People don't realize what they are asking of a mail order tune. Its like trying to sight a rifle scope in without firing a shot. Worse really. Its like asking SOMEONE ELSE to sight your scope in for you without firing a shot. If you've ever sighted a scope in you know that you need to fire shots, adjust, fire shots, adjust, repeat several times before you hone in on your target and are comfortable with the results. And even then if you give the rifle to someone else they will shoot differently than you did.
Even though I have the program to do the tuning, I wouldn't feel confident enough in my ability to use it properly to just go get on a dyno and start tuning. I would want someone there to help me my first few times.