Okay, you asked for it! To start with, I asked a local DCC expert which decoder would be best for my two locomotives. He recommended one - which I ordered. Once I received it, I test fitted the new board to see how much modification the frame needed. Then I started grinding. Unfortunately, I ground off so much that the frame became frail and broke. At that time, I called the DCC expert back up and said "What the hey? This thing still won't fit." At that point, he confessed that he had recommended the wrong decoder. Soooo, now I have just received some new frames from Atlas and am thinking of sending them to Aztec Mfg. to get them milled to accept a Lenz GoldMini-W decoder with golden white LED’s. Thing is, before I dump another $58 bucks into this engine ($44 for the decoder and $14 for the Aztec milling), I thought I would just put that money towards a brand new engine and keep my GP-7's DC as they still work great on the 00 setting at the club (except for the reverse loop). Sooo, I went down to the good ol' Hobby Bench and bought myself one of them new Atlas engines with the decoder already installed ($130). Took it out to the club that night all excited only to find the thing would not respond on the factory 03 setting. Finally after a while, we got it to move a little of it's own accord to discover that it was extremely lethargic at accepting commands (like 5 seconds), and it had a top speed of about 35 scale mph. It almost seemed like it was stuck on a momentum setting because every so often it would just stop and then it acted like it had to let the momentum build up again before it started off at a rip roaring rate of a snail. Finally, we pulled it off the track and inspected the wheels (which we should have done first) to find out that they were absolutely filthy. Hmmm, brand new locomotive, lotsa problems, filthy wheels. At that point, I decided to return the locomotive. IF I had of cleaned the wheels, it may have improved the performance BUT, it did not sit too well with me that I had purchased a "NEW" locomotive that had already been run enough by someone else to filthy up the wheels.