If you buy the Katana 600 (which would be a great choice) know that it will need some mods to make it more peppy. When I bought the Katana I did not want a "Street Sport Bike", I wanted a sport touring style bike. The Katana is perfect for this but I am used to something with nutz. I did not want a rocket but wanted to make the 600 a liitle bit more respectable. 1. I installed a D&D carbon fiber slip-on muffler ($500). It is loud, looks awesome, and the true carbon fiber means that you can ride it for hours and the canister will not get hot to where you can´t touch it (good for passengers). 2. Get a K&N air filter ($50). This will also add HP and will free up better air flow. 3. Since I installed the filter and muffler, I now needed a jet kit, stage 2 ($125) and needed the carbs to get jetted (free). 4. It depends on what you want, top end speed or low end for take offs. I wanted the bike to take off faster so I changed the front sprocket to one tooth smaller and put on an O-ring chain ($240). With all this done it is a lot better and acts more like a GSXR 600 (not the handling part though). You might also want to port and polish the intake and exhaust and the cylinders. I did this and added Wiseco pistons. This added a lot more HPs. My Dad owns his own business doing machining and welding but does not usually do this type of work (for bikes I mean) so I can´t give acurate estimates. For looks I added a carbon fiber tank pad, carbon fiber grips, carbon fiber bar ends, and carbon fiber levers, all from Ebay for cheap! Thanks for reading and any questions just email me and I will do my best to answer your questions. Peace and be safe!