Geoff and Mike get the idea to build a miniature version of the Ripsaw, H&H's ultra-fast military tank. They call their newest invention "Mini-Rip" and market it to the general public as a recreational vehicle. The twins hope to finish Mini-Rip just ... (more)in time to debut at the annual Grass Drags, a large motor-sports event in New Hampshire. Meanwhile, H&H gets an order for three more SR-1 Subterranean Rovers and Geoff has to go down to Ft. Hood, Texas to show off the Ripsaw's amazing abilities in hopes of getting more contracts with the Army. Managing several large projects at once puts a strain on the brothers' relationship and jeopardizes the completion of their latest and greatest machine.