Considering HPTuners ... Wondering if its the right choice for a stock 08 STS LH2

[Ludacrisvp]

I have been considering getting a tune on my STS and have been trying to decide on the right tune method to go with.
Basically HPTuners, EFILive, or a random professional shop that would hopefully be local.

2008 Cadillac STS AWD V8 LH2 Northstar 6L50E 3.23:1 ratio 320HP 291? torque

My car is completely stock for drivetrain / performance wise, and aftermarket performance addons are slim to non-existient.
There is an option of getting exhaust done but I don't plan on that, and according to everyone the stock air filter setup flows
more air than the NA version of this engine can use, so no need for a CAI. So it will live its life stock.

Basically everyone will just say sell it and buy the STS-V instead, that doesn't work for me as I wanted to have AWD
and I couldn't justify getting one as a Daily Driver.

Questions being:
1. Is it worth it for my car(s)?
2. Will it be able to do what I am looking to achieve?
3. Anyone have advice on creating a tune? or perhaps know someone that has a tune already made for what I am looking for?

Looking to get this out of a tune:
1. Improved throttle response (this is my first drive-by-wire car and the throttle lag is very annoying, my 02 DTS w/ 300HP FWD N*
was much, much more responsive than this is) it seems that unless I have it in sport shift mode 100% of the time there is a very
noticeable delay before RPMs start to increase and any acceleration begins.

2. Likely some kind of transmission changes - was reading the thread about the "6L80E TCC Apply Issue" and was wondering if it
also applied to the 6L50E that I have. I realize that having an AWD car my mileage will always be worse than a RWD car but it
would be nice to improve it a bit if I can if the TCC is setup to have desired slip. Tweak shift points on the transmission or shift behavior.

3. Raise speed limiter (mostly just because I don't like the thought of being artificially limited, not that I plan to go that fast.)
I do have the stock V rated 18's so my limiter should be at 149MPH but due to some intermittent suspension issue that doesn't
leave a code behind I am limited to 120MPH ... which I think I have narrowed down to a bad front passenger shock that is leaking
the Magnetorehological fluid. This will be getting looked at by the dealer this week to confirm and hopefully replace.

4. Possibly improve mileage when cruising - car is EPA rated at 14/21MPG.

5. Any suggestions for other things that should be done?

Anyone have thoughts / ideas for me on this before I go out and spend the cash on it and either end up disappointed or not being
able to accomplish any of what I would like to do.

And am I correct in assuming that the scan tool will be able to get full details on any DTC in the system like a Tech II could do?

[FASSTRUK]

You will be able to accomplish all of the above....but learn all you can first, and get a wide band afr gauge installed. Read the stickies and other comments about tuning, the tuner is absolutely money well spent.

[Ludacrisvp]

You will be able to accomplish all of the above....but learn all you can first, and get a wide band afr gauge installed. Read the stickies and other comments about tuning, the tuner is absolutely money well spent.

Good, I was hoping I didn't have my head in the clouds on this.

Thanks for the tip, I'll look into getting one ... any particular brands or known to be 'gimmicky' / inaccurate gauges to avoid? Just want to do it right the first time out.