Stock ebrake does suck but there are some options if you want a stronger ebrake.
1. Easiest and cheapest option is to upgrade your drums to projectmu shoes. These dont melt and have a cold bite for instant lock.
2. If you are serious about a dual caliper setup, you can have someone make one for you. Look up a guy named George Marstanovic, he may be able to help. There are several kits made for the 350z which the setup looks very simliar to the 370. I wouldnt be surprised if it works on both. My buddies at
Slideshop Motorsports have created one that I was going to test but haven't got around to doing this.
3. Dont use the ebrake technique and just clutch kick your way around the course... My favorite option