I have a L67 scanmaster that I dont need anymore. Im not even sure if you can get them anymore but its one of the best things i ever bought for my GTP.
Some info for those who dont know what it is...This stand alone product is compatible with all 1997-current L67-powered cars. It will display many (21) computer modes for tuning and also display and clear trouble codes. It can capture data for recall so you can see if your car was rich or lean it can also see spark knock
http://www.3800performance.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=SCAN
$200 firm (+ shipping if needed)
Some info for those who dont know what it is...This stand alone product is compatible with all 1997-current L67-powered cars. It will display many (21) computer modes for tuning and also display and clear trouble codes. It can capture data for recall so you can see if your car was rich or lean it can also see spark knock
http://www.3800performance.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=SCAN
$200 firm (+ shipping if needed)