Richard Holdener
December 14, 2006
With the installation of the Comp Xtreme Energy cams, Project RSC was finally beginning to make some serious power.

Things were about to get serious, as our '96 Mustang GT (a.k.a. Project Redheaded Step Child) was about to be treated to not only a set of performance cams, but also a set of long-tube headers and a cat-less X-pipe. You will remember that we subjected the 200,000-mile, non-PI motor to some minor mods in Part 1, then followed that up with some well-deserved maintenance items. After fresh oil, plugs, and wires, we were off to MagnaFlow to find some hidden horsepower (see "Project Redheaded Step Child, Part 3" in this issue).

The MagnaFlow exhaust mods included a new Tru-X pipe (which removed no fewer than four of the catalytic converters present on the factory cat pipe) and a new after-cat exhaust system. As expected, replacing the factory cat-pipe with the MagnaFlow Tru-X system significantly improved the exhaust flow. Though the after-cat exhaust offered less power gain than the X-pipe (as expected), the combination was worth as much as 15 hp.

When combined with the power gains offered by the minor mods in Part 1 (air intake, throttle body and plenum, custom chip, and underdrive pulleys), our lowly non-PI GT was finally starting to put down respectable power numbers. Unfortunately, and despite our best efforts, we still had not eclipsed the power output of a stock late-model PI 4.6. With '99-'04 GT power squarely in our sights, we decided to step up to not only a new set of cams, but also a set of long-tube headers.

Not surprisingly, the stock non-PI cams were pretty wimpy. For our daily driven '96 Mustang, we chose the smallest non-PI cams offered in the Comp Cams catalog. The XE262H cams offered 224 degrees of intake duration and 232 degrees of exhaust duration to go along with the 0.500 lift.

We made our choices because it was high time we started seeing some serious power gains. Unfortunately, minor mods are not terribly beneficial on an otherwise stock 4.6, especially on this early non-PI version. The throttle body is a perfect example. While the larger 75mm Accufab throttle body we installed in Part 1 (with the C&L plenum) certainly outflowed the stock counterparts, the reality is that the stock components were not restricting airflow through the engine, at least not by much. Were we to test the larger throttle body and plenum on a wilder (higher horsepower) combination, the additional airflow supplied by the aftermarket components would certainly show larger power gains.

The components work well, but the stock (or even mildly modified) motor is not in a position (power-wise) to take advantage of the additional airflow. Knowing the minor mods offered commensurate power gains, we decided it was time to bring in the big guns-well, at least the medium-range guns, as the big guns will come once we install the ported heads (and larger cams) and a new intake manifold. Short of forced induction, we expect the ported heads and intake to offer the largest normally aspirated power gains. With the heads and intake yet to come, we proceeded with a new set of cams and a set of long-tube headers. First up were the new cams. Since the 4.6 was to see service as a daily driver, our cams were chosen accordingly. With driveability high on the list, we opted for the smallest Comp cams in the Xtreme Energy lineup. As with all the non-PI cams available from Comp Cams, the XE262H profiles offered 0.500 lift on both the intake and exhaust. The duration, however, was skewed in favor of the exhaust, with 224 degrees of intake duration to the 232 degrees of exhaust duration. The 114-degree lobe separation angle improved idle quality and helped produce a broad torque curve. We have employed the XE262H cams on both PI and non-PI motors in the past, with excellent results.