I have a '00 with the 4.7 v8.The exhaust is pretty rusted though. The muffler itself is rusted with holes, it has a small leak, and there is no tailpipe. I was wondering if that would affect mpg and how the truck idles? I've only had it for about a week. Any info or thoughts would be great, thanks!

 

just rip the muffler off exhaust fixed. plus will sound better as for mpg i havent noticed any difference in my truck.