There are free programs out there that will let you view things that are happening but not change anything. You still need the cables which can be expensive.
I have the DHP PT. Bought it used for $200 and it's probably the best $200 I've spent. Plus I can tune any GM V6 car from 97-05.
i have to try to figure out something soon until i can afford a gauge any idea about where these free programs might be located ?