Well done. Not wishing to steal your thunder either but Evo VIII MRs and Evo IXs only have to be tickled slightly to produce a very reliable 400 bhp/ 400 lb ft car. My own Evo had 404 bhp and 390 lb ft with just a decatted exhaust, cold air intake and a good remap. The IX is even easier to tune due to the mivec engine.
Your friend's IX must still have the cat in situ and there is no way it has been remapped as the gain is fairly pathetic over the standard 280 bhp car. If it has been remapped, he needs to find a better mapper as even on completely standard cars (with stock/catted exhaust) you can get around 340-350 bhp with a good remap.