I purchased the GTM stage 2 kit and downpipes csc lines n clutch and I'm at about 12k. Still gettin gauges, exhaust, oil cooler and then a tune.. And I'm sure there will be little stuff here and there that I'll need to get. 15k I'd say is a good general cost with just the main parts but still need to leave room for misc items and for worst case scenario. I'd set aside 20-25k

If you're not going for ridiculous power than it can be done for 10-12. My total was about 11.5. That was with a stage I TT with external WG and 3" down pipes. Also added a 34 row cooler, boost and AFR gauge along with a FI 3" non resonated exhaust. I was using the stock clutch and it worked fine as long as I stayed at 8psi. I also did my install myself. That saved me probably close to 2k.
I would agree with others that $15k is a safe estimate for most basic TT installs. Obviously there are endless additions that can push the price well above $25k.

Unfortunately i am one of those guys that wants a ridiculous amount of power even though we all know it isnt really needed. Realisticly i would want to run around 9-10psi for a DD and be able to up the boost when needed and make some serious power. I drive my cars the way they are suppose to be driven, if the motor blows, oh well... That just means its going to come back harder.

We have a stage 2 GTM twin kit sitting on the shelf just waiting for a new home. :)

hmm....PM'd!