Both are good however, if you plan on putting 4:10 gears in, I hear you can only set the ratio to 4.09 w/ the Diablo. If plan on having your car dyno tuned though, check what your local guy uses and get that.
I have a ton of mods done - none require a tune, however I did install the JET ignition module that richened up the fuel and advanced the timing. MOD LIST: www.cardomain.com/ride/2382372