The stock Si engine makes ~100 ish HP. I'm making 135 on mine right now, and plan on bumping that up to around 150 soon, but after that the general findings on the old EW blocks is that the stock rods don't like to deal with that much extra stress.

No matter what size shot you use, you're going to want to retard the timing a few degrees just to make sure you don't pre-ignite. The EW engines like advanced timing, but if you're going to alter the oxygen content with nitrous, it can turn real bad real fast; especially since the Si engine has both vacuum and centrifugal advance. AKA, step on the gas, timing jumps up to facilitate hard acceleration. Once you come up through the revs, the timing doesn't really settle down until about 4000 RPM [where it is still advanced over the static setting], which means you only have 2500 RPM left to redline [even with the teg ECU, the cam will really only make power to 6200], and in gears 1-3, the timing never really does settle out too much.

The other thing to consider is the mileage on the engine. 100k miles on a Honda isn't bad, 100k on an engine that is over 17 years old could cause sprout some gremlins.

Just some things to keep in mind.