Some swear by them, others just swear at them, any pipe is just going to work well at a certain RPM, lots of trial and error. Like sbest stated, you can vary the length of the primary to effect fit and performance, (longer = better low-end at expense of top-end) The plating on these is very thin, you can easily scruff it up with steel wool, then paint to suit. BTW, these pipes are LOUD, keep that in mind if you have easily offended neighbors.