i found an ls motor i'm thinkin about buyin and it has gsr gears and ls final drive. ive never seen this set up before, any downsides?

 

If everything is working fine then the here are the pluses and minuses

plus:
more torque to the ground than ls tranny
lower highway rpm than gsr tranny

minus:
not as much torque to the ground as gsr tranny
higher highway rpm than ls tranny
lower gearing top speed(using ls stock redline) than a gsr and a ls

I think thats it if I think of anything else I'll let you know.

 

Well, 1st and 2nd gear are the same ratio for the GS-R and LS, so the gearing will only be shorter in 3rd - 5th. Not exactly how I'd do it. If you want the same final drive as the GS-R you can install the ring gear and countershaft from a B17A's tranny, or if you are willing to change the diff at the same time you can use the ring gear and countershaft of a 3rd Gen GS-R.