Congrats on the new 379 and
We have a 2007 GT 370 with the Ford F53 Chassis. It does real well on power. I added the Banks Power Cold Air Intake System. Bought it at Camping World and did the install myself. It really made a difference from the response of the pedal to the engine. It doesn't shift as often going up hills. It maintains speed up hills better than the factory set-up. Better gas mileage? I hope so, haven't been able to go very far this spring to get a good reading.
We've haven't had many problems just minor things that I either fixed or the dealership took care of. FR has always been very good about any request we've had for parts etc to fix things. We thoroughly enjoy ours where ever we go.
One place I always recommend for RV things is WalMart. They have a pretty good selection of necessities at real good prices. Enjoy your new RV!! If there's anything we can help with , other than payments, just ask.