Recently I completed an initial implementation of Google Tag Manager on VPASP version 7.0 shopping cart, and I’m about to begin another implementation.  It wasn’t terribly difficult, but it was a little tricky to get the ecommerce integration set up properly and I implemented a DataLayer within VPASP’s order confirmation page logic to make it all work.  Please send me a comment or contact form if you’d like more info about GTM and VPASP.  (honestly I was surprised  not to find any other writeups on the topic)