not being funny but if its ver low comp then it could be worn bores pistons head head gasket or simpley it was low comp and the advance part on the map chip ecu is not addvanceing the spark to alow it to rev had the same problem turned out to be the chip need more advance of spark so they added 5 degres of spark its now flying but that was because it whent low comp out of the blue it whent bang in the end worn pisstons and bores