I have a Sly Dual Carbon kit and really like it. The Diesel kit has a longer control bore which is nice but has fewer backs to select from (I think
I hear great things about the DW freak kits tho there tips look a little more fragile then the Sly.
MacDev Militia: Clone GTi with Shift Kit, GTi Valve, Pooty Bolt, & Violent Series Trigger
dp Fusion FX with TechT HUSH Bolt & TechT LAW RAM
Sly Pro-Merc Diesel Barrel Kit, dye Rotor with Exalt Speed Feed, & Crossfire SS HPA 68/4500 Tank.