that pipe is real restrictive,and isnt much quieter(when new) than stock from what i gathered from just about every review i read written by someone who wasnt in bed with the manufacture
i do quite extensive research on items such as this before making any decision
its been awhile,but if i recall (not positive,as i said its been a while),that pipe also has to be repacked every 30 or so hours,,,,folks were saying zero HP gains,,,,,none,,,,,,and no noticable DB's change after a few runs,,,,,again ,just what i read in individual reviews
the pro flow kit on the other hand,i can speak from personal experiance,,,,very noticable gains,,,,but i did drill my airbox
i was somewhat concerned about drilling the lid,and going through the deep snot,,and last weekend i attempted the deep one with the bear claws on and had it buried up to the seat (15 3/4" clearance to the bottom of the foot well) ,and the mud only got to the top,but not over the lid,,,still pretty close though