My PCM was not reprogrammed at all . I don't even have a reader at this time but am going to get one . Any suggestions on where to find one for a reasonable price? I looked on Ebay and didn't really like what I was seeing . This is a 1998 year engine , Doc. The only bung that needed relocation was the pass. side and it's probably about a foot and a half further back than where it was but the wires still reached . I wondered if that was a factor myself . I need to go get a scantool , at the very least . I have no way of knowing if the forward O2 sensors are any good .Is there a particular brand that anyone can recommend ? I think that one of the rear ones got moved to the front but I don't think this matters does it ? So , is the estimate of 2/3 of actual HP fairly accurate until I get this matter resolved ? My truck totally hauls ass now . It's hard to believe that I might get another 80 to 100 HP just by getting the sensors back online . Just wondering .