So, I just bought the K&N 77 from biglg, I already have a Flowmaster Super 40 (single out), I had the sound resonator and 2 mufflers taken off, do I need to have the computer flashed or will the computer adjust itself?

Note***** When I went to buy oil and filter yesterday I was looking in the owner manual for capacities. I noticed that it says the 4.7 and something else (can't remember the other engine and too lazy to walk out to the truck to get the manual) use 87 octane fuel BUT,....... the 5.7 is supposed to have 89. This is news to me. I added 89 once before because I always thought the occaisonal upgrade might blow some cobwebs out, but now I guess when I want an occaisonal upgrade I will need to steal gas from my wifes Beemer.

 

Yea my 03 says to run 89 in it and have since I have owned it. Not sure if 87 would hurt it or not, maybe sparkknock.

 

You do not need the computer "flashed," that is what the dealer (or high end performance shop)does. However, it may not be a bad idea to "reset" your computer yourself, it will adjust to your mods faster.

If you have a Hemi, you should run 89 octane gase ALL THE TIME. Chrysler highly recommends it, however claims that 87 octane will not harm the engine in any way, but you will not get the rated performance.