maybe you are having piston ring blow by? Did you crank up the boost after tuning for a specified boost level? Is it running on all four cylinders? What about your clutch/pressure plate, maybe they are slipping due to over loading? That would cause you to not put any power to the ground. Also, plug your laptop into your hondata and check you ignition maps and fuel maps. I know with K-pro for the RSX-S you can do such things...just trying to help.