When modifying for big power, ensuring transmission durability should be just as important as making sure the engine won't blow. And that's why ATS Diesel Performance offers a torque converter upgrade to accompany the 2007.5-2010 Ford 6.4-liter Power Stroke.

The diesel V-8 from Navistar is plenty modified, and the extra torque generated can wreak havoc on the factory five-speed automatic if it isn't protected. The ATS Diesel Performance torque converter has a wider turbine and impeller to accommodate the hydraulic fluid for best stall speed. Strengthened internals help handle any extra stress exerted on the gearbox, too. Pricing: $1,450.00 (est.)

ATS Diesel Performance