Hello,
I also have the Alex Peper Scanner.
The scanner offers the option to scan enhanced parameters on 3 different interfaces....Which allows you to scan "Most Cars".
For a little bit more you can got with Autotap. They offer only one interface for a bit more, but I really like the user options on A-tap.
If you are looking for a scanner that you only intend on using for GM only, I would reccomend Autotap. You can get Autotap to scan all 3 interfaces, but you would be spending 3 times more than you may want to. Last I looked
www.pfyc.com was offering Autotap.
On the other hand, for the price, if you want to scan GM, Ford, Most Imports, and Chrysler, you may want to look into the Alex Peper tool.
Later now,
Clint