Si brakes are about as sweet as sourcraut.
The "easy" upgrade for the 4G is to get the 90-91 Civic EX (AND EX ONLY!!!) front knuckle assemblies. The Ex use 10.2" rotors and teg brakes.
DO NOT GET 90-93 integra front knuckles! Although they use the same caliper, mounting bracket and rotor, the knuckle itself is a slightly different shape and will fuck up your suspension geometry hardcore. I can say this from expereience. Also, the 89-91 JDM/EDM CRX SiR knuckles are the same as these and should not be used.
The next step up from the 90-91 Ex setup requires you to make some choices.
The easy and expensive choice is a 11" fastbrakes kit with 11" rotors and wilwood calipers. Great kit, great brakes, questionable value.
If you feel creative, you should read up on the old hybrid archives (hybrid.honda-perf.org) and look at the 4G bigbrake upgrade pages... The "classic" way of doing DIY 11" brakes on a 4G is to use the 92-95 Prelude vtec rotors redrilled from 4x114 to 4x100, 94-95 Accord Wagon (same part # and caliper as ITR) calipers, and then get the calipers machined to fit the slightly different offset of the rotors. HOWEVER... 1990 VW Corrado rotors are the same size as the 'lude (11") but they have the same bolt pattern as the EF (4x100) and they have (I believe) a 38mm offset, which would make them a more or less bolt up deal without getting the calipers machined. If you wait a week or so, I'll be able to tell you for sure if the Ex/Wagon/Corrado combo is plug n play or still requires machine work.
And FYI, the corrado rotors DO NOT clear the hub assembly on 5G knuckles - only the 4G guys are lucky enough to have this one.
