Is anyone using this yet and if so how is it working. I'm debating between the 2 they have. I'm not sure if I want to remove the pipe yet. I want the mileage but at the same time I dont want to watch my warranty go to hell.

 

That and a tuner and mutually exclusive. Any tuner will void your warranty, so from that aspect neither tuner is worse than the other. If you're scared of losing your warranty leave it stock, its as simple as that.

 

There is warranty, then there is Federal Emissions violation. Both come at a serious cost to you. However, with diesel at 5 a gallon, it begins to look better and better.