Filter is clean. I have been noticing for awhile that I have had no smoke coming out of my exhaust even when I get on it or when it is under load going up a steep grade. I am having a hugh loss of power. stuggling to make it up the grade to san diego that I have made many of times with no problems. The only change I made was going to a 4" exhaust. The programmer company (hypertech) says that is the problem. He said the exhaust puts no back pressure on the turbo and lets it spinn up rapidly and creates more boost thus more EGT's .