Just ordered the GTB 5.5 system. It's going in my Pro-4, and should be a good race setup. It was a great platform for 19T spec, I expect it tp be awsome with all the extra power. I'll be sure and report it's performance. This will be the 1st time our club runs an open mod class. So we'll see how well the GTB system stands up against a bunch of brushed mod competition...