building a emaxx form scratch

I was going to buy a emaxx from a friend at work for cheap but i was going to replace almost everything on it. so i have decided to build it form scratch. im giong to be using the flm exteneded chassis. and all rpm arms, shock tower, even the new rear conversion to get ride of the toe turnbuckle. also going to be using revo shocks on it so i can get it low to the ground cause im building a all out drag emaxx.

I was just wondering what kinda diffs should i use. should just keep with the stock ones or is there a nice upgrade that could make it go faster or something. i would think the stock ones would be strong cause in my revo i never went there a diff. i only took them apart to clean them out and re oil them.

thanks! I well be sure to post up some pics of the build once i start it.