Now that my car is paid off and I own it i wanna do some MPG increasing experiments. Alreadt got a SRI. Anyone have a header or downpipe/ exhaust I can buy used?

 

I don't have one to sell, but I did just put one on myself and did some experiments too.

I bought a Megan Racing exhaust header, first off. I then tested my mpg on the highway before I put it on. I went 55 mpg behind a semi-truck for roughly 10 minutes and got 38-39 mpg. Then I put the header on, did the same test in the same area of the highway and got 41 mpg. I used the mobile app "aCar" to record my mileage more accurately. Before the second test I filled my tank as well.

I bet your mpg will be different due to the SRI, but this should give you a rough idea what to expect.