easy to install, much quieter with hpx, combined with fpx equals order in drive thru without turning off truck.
good product well made.

Great Price, FAST Shipping, Quality Product. Easy install. Tip: CLEAN your engine really good before installation.
Thanks again Riffraff diesel, will be Buying from you again.

Hardest part was climbing on top of motor to change out/install(is a 4x4). Tight area, but I did this when installing air filter kit so the drivers side was a little more open. Plugs came out easy with 1/2" ext and a swivel socket. Install require wrenching in painfully slow increments. Glad when done, but starts much easier and seems smoother when operating.

Very nice product for the money. Install is straight forward and very easy without having to remove any engine components. It is hard to tell what this product by itself did for the engine noise and performance because I installed the FRx at the same time. The HPx and FRx together made a very noticeable reduction in engine noise and vibration. Idle is nice and smooth and low speed acceleration is more responsive. Just a quick note to RiffRaff Diesel, after spending over 250.00 could you guys at least throw in a sticker/ decal so we can show our support for your products.

Very noticeable difference. Idle is much better and quieter. Highly recommend

The HPX was easy to install, fit was perfect, really cut the edge off the noise, and smoothed out the operation.

cant believe the difference in drivability and idle quality.

Easy install!!!
Instantly quieted down my motor and smoothed out idle.
Unfortunately I now dont have an excuse for not listening to my fiance. wish i had done it sooner for sure.

Super easy to install. Had to bend it a little bit to get it to fit but it was no big deal. Didn't really notice a difference because I also installed like three or four other mods at the same time. But for the price you can't go wrong.