I have seen plenty of final drive upgrades, but they dont seem to include the LS tranny. Does the final drive for the gsr bolt directly, or are the boxes too different?

 

I just did a thread asking the same thing. The gsr is a 4.4 final which will basically give you a gsr 1+2 and tall 3-5(only slightly shorter than ls). A custom 4.7( has to be because different # of bolts on differential than type r) will give you aproximately a b16a 1+2 and slightly shorter yet 3-5(b16a is still shorter on 3-5). A 4.9 seems interesting with a shorter than b16 1-2 and ever slightly taller than b16 3-5. For the money getting a b16a tranny in good shape(rare) would be a better investment esp with a stock lsd. I personally am runnin an ls and ponderin the 4.9 just to try it(not like you couldnt sell the final if it didnt work out. The other problem with the gsr differential has the type r # of bolts so you would need the b16a final(also 4.4). On the civic faqs page there are links to gear calcs so you can see the charts and even compare charts of different gearing.