Just wondering if anyone has had expirience or dyno with both on same exhaust
For example let's say someone had xxx exhaust with HFC and then later switched to test pipes how much power would be gained if any ?

 

There are many posts on here and also if you search on Google or YouTube. Vosseng37s and 1cleang on the forum have posted the gains for fast intentions and you could go to Ark's YouTube page to see their numbers.