The VW has the tank under car and does not need a cell. As long as the cage has a dash bar and anti wheel tubes , the cage should be fine.
Our case, VW Scirocco, we took out 100#, added a fire system and slicks and went racing with the IT legal engine. The car ran pretty well with full glass and all steel.


Next , removed front bumper and put the battery inside .

This year we have a fresh bottom end, light flywheel, some compression, prod legal cam, better fuel system. We need about 2 sec to run with the bigs. A real engine is a start. Real tires next maybe, but that sets up gearset issues.

The Golf , set up about the same is still 100#over.and 2 sec slower tho it handles better and carries more speed midturn. ( due to the rearsteer)
This car was a good IT car until I peeked at the flywheel and the cam. both are NG for IT and I added the HP labels.