Having said that - all the modders that drove Wiras no longer drive wiras. I wouldn't say what I learnt is hard - just expensive. I didn't want to just change the engine to a Mivec or GSR and be done with it. People just Justin Merrill in America have psychotic drag 4G15 machines that need a wastegate for idling cuz the supercharger runs at 0.8 bar pressure on idle. People like Justin are the true mad fellas. 1. Yes it is. Remove the head and the piston tops are revealed lor. 2. Degreaser, a brush and a high pressure water hose. Or just use diesel to wash your engine. Just remember to rinse it well after washing. 3. higher compression will just mean higher power to some extent. Yes - more heat too. But all depends on how much you go. Even if you fully skim your head to the max it won't do anything too drastic other than sometimes knock at high revs if you're using low octane petrol. If you're talking about high compression pistons and skimming, then you better hope your ECU can adapt otherwise you might need to use high octane petrol already.