The "sound of hole" in my muffler was killing me but it was sunday.. I cut a bigger hole, removed everthing what was left inside and put a steel sheet patch (stupid idea I know, sounds ****ty and I have to wear
while driving) but I noticed higher fuel consumption and light hp increse. I'm aware the muffler design is to slow down the fumes, keep some pressure etc. but hypotheticaly if I put a device (with a switch), which could change the diameter of the exhaust pipe would it be possible to have extra, let say, 2hp for overtaking and -2hp for highway mpg? I know it's not worth it but am I right or it's just wrong way thinking?