I have one. I have CTR cams, I was running +2in +4ex for 26 deg of overlap on the GSR muffler and exhaust. I made the most power here. Once I put on the ITR muffler, I was able to run my overlap out to 34 with a slight bump at 4500rpm. Before I tried this with the GSR and it made a valley at 4500rpm and had a dead spot like the car wasnt acclerating until like 5500... I have +4, -2 in the cams now and it made great power at 18BTDC above 6K... not to mention everywhere else. yummy =) This led me to believe that the 98 ITR muffler flows much mo bedda. I like the fact that it is actually quieter than my stock 99 GSR one.