The LRD has the most grunt with the FMF prolly second in that area.
Trinity and Hetrick pipes are my choice for low and top end.
The CT has a bigger expansion chamber thus it's supposed to give higher rpm's.
My national motor with a Trinity can rev 13k+ with a HP of about 15.
It's been a long time since I been on a dyno but those were the numbers.
** dyno's are fickle** LOL