I changed this out and I cant say that I had a huge surge in power, but I can tell a bit of a difference. This needed to be done vs waiting and its pretty inexpensive. The customer service is really GREAT! If I have a question they get back to me quickly. I am the stage of life now that the customer service is just as important as the product and the price. Really appreciate Riffraff Diesel! Thanks Clay!!!

I ended up getting the FRx later and it came with this kit and I used the recommended gold spring. Noticeable improvement.

Spring kit works good and is easy to install. I recommend buying the upgraded billet housing riffraff offers because i

Quick 15 min job and brought the truck back to where it should be I used the gold spring old spring was getting week after 180000 miles

I couldn't tell the difference between the silver and gold springs. Either the difference was very subtle or I got 2 silver springs. I took a guess at which I thought was gold and put it in.

Being a shop owner! This product really help with smoother idle, better take off, fuel mileage, I would recommend it for stock or tuned.. Wanting to make real power upgrade the fuel systems completely!

Complete kit, has the seals and springs you need to do the job. Tried one from Amazon and I couldn't keep it under 80psi. This kit is perfect, 63psi and made in usa! Recommended for everyone that hasn't updated their springs yet.

Took less than 10 min. And I have a greater throttle response!

Went with the gold spring. Bone stock truck, NAPA 6637 air filter is only mod. Better throttle response, and allows truck to get into the higher RPMs quicker. Doubtful it helps with mileage, but I don't think it hurt it either.