The stock clutch certainly wasn't going to hold up to the abusive torque curve that this system was going to produce. Urist called his friends at ACT to build a clutch to withstand the abundance of torque. The company shipped a single-disc unit that was rated at 920 lb-ft. At the time, Urist thought the clutch rating was sufficient. In the end, our test subject cranked out 1,015 rwtq, and the clutch survived the onslaught on the chassis dyno. The IRS is a different story; the wheels bowed inward during the dyno pulls. It lived, but the question was, for how long? We think the axles will snap easily on the street, even with straight-up radial tires.
Anderson Ford Motorsport was also tapped for its PMS engine management. We were impressed-the PMS fired the factory coil packs at 44 psi of boost. Urist also used the PMS to dial-in the fuel curve, which took just three dyno pulls to get it running smoothly.
The engine was responsive to timing and rpm changes. Urist opened the wastegate by making one turn on the knob and started with 14 degrees of timing. Utilizing just 4 psi at the turbos and 16 psi at the manifold, the power registered 611 rwhp and 646 rwtq. That's a far cry from the 385-rwhp output that bone-stock '03-'04 Cobras normally put out on the Dyno Edge chassis dyno.
We wanted to see some big numbers, but the Hellion crew stepped things up, one chassis pull at a time. Another run was made at 14 degrees and at the 6,000-rpm limit, with the only change being an increase in boost. Output was 846 rwhp and 720 rwtq, as boost registered 23.70 at the turbos and 38.50 in the manifold-this combo needed more timing. Urist inserted his opinion: "These turbos needed to be hit harder down low, and the fuel curve had to be leaned out some more."
It was time to make big power, so the timing was upped to 16 degrees, and the Cobra was run up to 6,500 rpm. The results were 1,048 rwhp and 900 rwtq, with turbo boost coming in at 26.8 pounds and the manifold registering 41. One more pull was made, and Urist cleaned up the fuel map a bit and put the timing at 19 degrees. The turbo boost showed 27 psi, while the mani-fold saw a peak of 44 psi due to increased engine rpm. Spinning the blower harder will result in a greater manifold pressure. Final output was 1,188 rwhp and 1,015 rwtq.
The combinations are limitless when you factor in different pulley and turbo setups. Don't think for a moment that this setup is strictly for '03-'04 Cobras. Running a Roots-style blower on any engine with a single or twin turbocharger setup will produce great power-just be sure your engine is capable of handling it. Compounding boost can yield excellent results, even at low turbo levels like 13 psi (roughly 22 psi at the manifold), and make a nice, healthy street machine out of your Mustang or Cobra.
A ProCharger bypass valve is used to relieve pressure when the driver pulls his foot out of the gas. All of the boost has to be vented to the atmosphere to prevent it from backing up into the turbo housings. Urist utilized ProCharger's massive race bypass due to the big boost potential of the system. | 
Two boost sensors were plumbed into the system and were recorded by a Race Pak datalogger. One sensor reads up to 50 psi (measuring the turbo side), while the other was good for 100 psi (reading manifold pressure after the supercharger). | 
We added two boost gauges for instant gratification, but they proved too slow to keep up with the boost acceleration. |
Here's a printout from the Race Pak datalogger showing the boost curves on one of the runs. You can see how quickly the boost ramps up and holds steady. The turbos were churning out 24 psi of boost, while the blower compounded it to a bone-crushing 42.85 psi. | 
Fuel is important, and Urist went overboard with a return-style system while also using a Weldon fuel-pressure regulator, fuel filter, and 2345 fuel pump. | 
The tank now features a sump, and we ran on VP 112-octane racing fuel. Future testing will be conducted using pump gas with methanol injection as well as straight E85. |