I have an 89 635csi and am considering putting a performance chip on it. I noticed that HMS carries a "Landshark Performance Chip" that claims a +43 horsepower increase and a 21 ft.lb. torque increase. Has anyone tried this chip? I have heard mixed things about whether any of these chips (Dinan, Conforti,etc.) really work or not. Any information would be appreciated. Thanks.