ok heres the deal i have a 2001 celica gt with a izzfe 1.8L engine. mods that would effect engine proformance are a cold air kit (with redone ecu) and a magnaflow exhaust recently added. the car is a standard trans. the other day i was driveing home and raced a mustang. due to many suspension mods i was able to keep him in sight however when i came to a stop i head a noise that was new to me. so i pulled over and opened the hood. the engine has a internal knock that sounds like a click. it gets louder as it rev's up. so i drove home and parked it. came to find that it has basically zero oil. so oil was added however click/knock stayed. oil light and check engine light never came on! i was told it was problly my head gasket but there is no visual leaks even with car running. exhaust is clear so no signs its burning oil. so idk where the oil is but new oil stayed. also i checked the coolant and no oil there either. someone also said a piston might have cracked so i pulled plug wires one at a time and was sure to find all cylinders fired. the noise is 100% inside the engine and idk what to expect from here. feel free to post possibilties. car runs ok and drives the same almost no power difference. but click/knock sounds are loudly heard