I got the car a year and half ago with 266k on the clock. From day 1 to now, I've been religiously monitoring the car performance through my phone app. When I input the current mileage, amount of fuel I pumped in and the app calculates the true mpg from the last entry. I also reset the mileage trip between each fill up, that way I know how far the car goes.

From that day up until two months ago the average was a solid 28.9 mpg. The fuel gauge in the cluster is actually accurate -- each quarter mark on the gauge was exactly 150 miles -- as in I drive 150 miles, the gauge would drop 1 full quarter. At 300, it would be half tank, and so on. At 600 miles, give or take, the car would take between 18.5 to 19.4 gallon. I could set my clock to this, it was so accurate.

Then up two months ago, immediately after I installed the stage 1 tune, poof. 200 miles gone. I went from 28-29 mpg down to 22-23 mpg virtually overnight.

I'm thinking of redoing all O rings with viton.

Viton for Mercedes Engines at FRYERPOWER HOME

Is this the only source? Is that still available?