i used to get a least 260 plus, but now it's 200mile or less. i have noticed that it does burn a little bit of oil, but should it be burning oil? i use Ams oil which is synthetic. if my cat converter is clogged what should i do to fix it. i also recently picked up a jdm itr header and i am in the process of buying a cat converter. but i don't want the same problem of clogging up the new cat converter.