All I have done to my Z28 so far is UMI Performance Short Shifter, SLP LM1, SLP Offroad Y pipe, and SLP MAF. Stock headers and everything else is also stock. I got it in Austin TX and then drove it on a 4 hour drive back to Texarkana TX the very next day. Right now I'm on my way back to Austin to visit my Mom and I can barely hear the exhaust once I get up to speed and get into 6th gear to cruise. And I have been cruising between 85 and 90MPH which is 2000RPM in 6th gear. It hasn't bothered me. It has a really nice rumble at idle and sounds really good when going through the gears! I like it! Everybody else with the LM1 says it's terrible! Idk if I'm just weird or if I accidentally got an LM2 somehow but I like the way mine sounds!