Going with the TPI is the best thing you could do, I am looking for a TPI myself, as far as the cost it really depends if you do it your self and if you get the TPI for cheap wich we all know you wont, but you're looking at about $1000-$1500, I'm looking at about $800 for my truck but if my brother in law gives me his TPI from his Iroc, he wants to part it out and I asked him for the TPI and he said yes, so for the installation alone since I dont know how to do it and I really dont want to mess with the installation I got some estimates and they're all around $800 so good luck and sorry for writing so much.
LOVE MY GREEN GIANT!!!