if you get your 4th gear rebuilt it will probebly be cheaper in the long run to do the whole tranny. if you're going to be putting down huge numbers with turbo then yes i would suggest the LS tranny but if its going to be your daily driver i would just go with the GSR tranny. i would just get they tranny rebuilt because you would have all new gears so you'll start off with brand new gears when you boost it.