The mod work definitely made the 441 feel bigger than it did when new. It ran alongside or slightly ahead of my 7900, which suggests that the 441 was putting out 6.5hp or so.
If you already own a 441, getting it ported may be a good idea. If you don't, it's a lot of money to spend for the saw and the porting work when a 7900 will do the same work for two or three hundred less.