we have tried that in other cars and have had durability problems with the 1-3 gears. we tried just using an ls 4th but gsr and ls 1-3 are slightly different and it was enough of a difference to drop too low in the rpms when going into 4th. we like the ratio of the gsr, its perfect, so ideally the best option is to simply stretch that gear out a little further with more rpm. its time to go through the head anyways. springs are cheap so it still follows the idea of what the car is all about 