I have my interior down to the bare fiberglass and I am installing Dynamat Extreme and some closed cell foil backed insulation.  (drove the car without anything in it and I actually pulled over to check to see if the engine was on fire it got so hot!  I guess a big block with headers will do that!)  My question is - the carpets I purchased from ACC came with jute backing in certain areas, I assume I leave these on even with the Dynamat and foil.  I'm assuming if I am adding a consistent even layer underneath the carpet I will still require the jute backing for the carpet to fit correctly or be shaped corrcetly?  Thoughts?

Depending on how thick the insulation you're adding is, you should be able to use with the backing still on it. You will probably have to use a heat gun in the rear compartment even though the carpet is probably preformed.