HI--I HAVE A CUSTOMER THAT HAS A 01 WITH THE TTS POWER SYSTEM 80 HP. UPGRADE. IT WAS INSTALLED 01/02. HE TOWS A 48 FT 2 RACE CAR TRAILER. WE HAD NO PROBLEMS TILL LATE IN JUNE WHEN HE WAS TOWING UP BAKER GRADE IN CA. THE TRANS WENT TO 3RD GEAR AND WOULD NOT SHIFT UP OR DOWN. HE PULLED OVER , SHUT THE TRUCK OFF, STARTED IT AGAIN AND ALL WAS FINE. WHEN HE GOT BACK TO VEGAS I SCANED IT TO FIND A CODE P0735--5TH GEAR RATIO ERROR. I HAD JUST GOTTEN A OTC MENTOR AND DID NOT KNOW TO LOOK IN ANOTHER AREA FOR MOTOR CODES. ANYWAY THE PROBLEM DID NOT HAPPEN AGAIN FOR A WHILE. BUT NOW IT HAPPENS ANYTIME WE HOOK UP THE TRAILER. SO WE TOOK IT TO THE DEALER TO HAVE IT CHECKED. THEY CAME OUT AND ASKED IF WE HAD THE COMPUTER UPGRADED? AND WE SAID OF CORSE NOT! then they said it had code po234 boost sensor (overboost) and po181 fuel temp. sensor. then they asked about the computer again!!!. i didnt know if installing a straight thru. muffler could cause over boost? so i tryed to call steve cole at tts 5 times today but he never call back and the nice lady on the phone said he was leaving for about a week- in the morning. the owner of the truck says the boost gauge hits 26 lbs in the big hills. the truck has 27,000 miles and the trailer weight is about 18,000 lbs. i dont know if this is a computer problem with controling the boost. just driving it hits 23 lbs with no trailer. or maybe a boost creep problem in the wastegate or solenoid.------------thanks for any help----len in las vegas