Hey everyone just have a quick question about my XJ. I've noticed lately that when I start it up the exhaust sounds just fine but after about 2 minutes or so it starts making a built cammed sound. It does sound awesome but I'm thinking it could be a misfire or maybe something to do with the computer not to sure. Just wondering if anyone else had this problem thanks.

 

What year? Motor? Transmission? Did you stick a Thumper cam in there and forget about it?