I don´t know the horsepower numbers. I´ve never ridden it without the "kit". It came from the dealer that way. It was about $600.00 US. That figure included the labor. I have spoke with someone recently that had an 883 and put the 1200cc kit on it. He said that there is night and day differenc in the 883 and the 1200. He is a big guy, too. Not as heavy as me, but no light weight. So, if I had to do it over again, I might just wait until I could afford a 1200. It cost about 1400 plus to convert after the fact. The sportster is a little small for me, frame wise, but not totally uncomfortable. Just not a long hauler. I hope to move to something more my size in the future.