I have a rattle in my 2006 s281-sc. I have it a 60-70 mph and 5th gear It sounds like its coming from the passenger floor board and its metallic like a heatshield. all bolts are in the tranny plate and all heatshields are tight has anyone else had these issues and if so how did you fix it?
I've read somewhere that there was a part that either needed to be modded or replaced by the transmission that caused a rattling noise. I've also heard that that was most noticeable when the car was cold so this may not be your problem. Does your Saleen have an aftermarket shifter that may be causing noise (my hurst does because it needs to be isolated better).
Finally the most important of the ideas if you're running a SC you probably have some kind of tune. Make sure the tune isn't leaning out when the engine is at load and is causing pinging. I had that problem with my 07 GT and was driving me crazy. Called Doug at bamachips, he sent me a new race tune with the timing stepped off and the problem was solved instantly.