I know this is sometime since your post but thought I would write to you anyway. I have used an SH .21 7 port engine. This engine was very fast. I used it some years ago at the SW tour in Texas and had no problems down the staights with anyone. The low end was great and a bit flat in the middle. I now have one SH .21 and had it flow tested and modifed further. This engine now is wicked and spent far less than $500 that the other guys I pass spent!!!