well, for those of you who replace your muffler, I was wondering what year of xterra you all have. I know that for 2003 xterra, it has 10 more HP than previous xterras ( from 170Hp --> 180HP). Someone told me that Nissan had different exhaust system on 2003 xterra which gives 10 more HP. So I was just wondering if I still want to replace my muffler with Borla muffler, will it still make any obvious difference????