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Stealth Stang Exhaust Modification - Yo, Exhale!
It Is Time To Dump The Clogged Stock Exhaust Junk And Go With Parts That Offer More Flow
Last month, we embarked on a mission to start adding horsepower to a new project vehicle at the MM&FF stables. The car has been dubbed the Silver Stealth Stang and belongs to our esteemed colleague, Ken Miele. For those who don't recognize his name, Miele is the contributor responsible for the tech column called Yo, Ken!. We added an assortment of induction pieces to help the 160,000-mile Two-Valve engine inhale easier. The upgrades didn't break the bank nor did they require special training to install. This month, our goal was to help the engine exhale better in the form of shorty headers, an x-pipe system, high-flow cats, and an after-cat exhaust system.
The Silver Stealth Stang began its project car life in the Dec. '08 issue when we added a complete Hotchkis suspension system. It helped the car handle the New Jersey roads nicely. Last month, we headed to Radical Racing where the gang installed a JLT cold air kit, a TFS 70mm throttle body, and a TFS upper plenum. Radical Racing proprietor Craig Radovich, cut a custom tune using DiabloSport CMR software and loaded it into the car with a Predator. Power went from a paltry 215 rwhp up to 225 rwhp, but the mid-range gains were enormous; at one point we calculated a rise in horsepower by about 32 rwhp.
On track, we were a little disappointed with the initial results thanks largely to the car being hot and the weather abnormally warm. The car had run 14.31 at 96 mph, a number we thought should have been in the teens. Miele did redeem himself and showed up to one of MM&FF's track days after the story went to print, where he knocked off a stellar 13.98 at 97 mph. The difference was much cooler weather, an iced intake, and an outstanding 2.00 60-foot time-that has never been duplicated. On average, we figure our original estimate of 14s should be expected for the mods. We want to put a lot of emphasis on track testing with the Silver Stealth Stang, because a lot of mods work better in the real world than solely in the dyno-testing world. Radovich is also a big proponent of track testing to go along with dyno results for that very reason, too. He says it best-you don't live on a chassis dyno, the real test is on the track.
With the car running consistently, it was time to make some more changes. This time we would open up the exhaust to help the engine kick out the extra air it had been ingesting thanks to the new induction components. Due to the mild nature of the engine, we decided to grab a set of shorty headers from Ford Racing. Complementing the shorty headers is a Bassani x-pipe and after-cat exhaust system. The stock pipes feature three cats per side and huge mufflers; the Bassani components are made of 2½-inch pipes and have a pair of high-flow catalytic converters. Topping it all off, the Bassani exhaust pieces are stainless steel, meaning they will outlive the car by being resistant to rust.
Once again, we relied on Radical Racing to handle the installation in its Atco, New Jersey-based shop. We arrived promptly at 9 a.m. and the Radical crew (Mitch and Lee) was ready to tear into our 160,000-or-so mile hot rod. The severe mileage meant they were contending with rusty nuts and bolts. Surprisingly, the shop prefers to drop out the K-member and front suspension in order to swap headers. According to Radovich, it's just easier, and since there is such high-mileage on the odometer, he was expecting some of the exhaust manifold studs would break off in the head. That would require drilling out the remnants, tapping the hole, and installing a Helicoil. We raised an eyebrow about dropping the K-member assembly due to time and effort, but the guys just laughed at Miele and I. Shockingly, they had the engine supported and the K-member removed in 39 minutes. The exhaust was buzzed off, and just as Radovich had expected, a rusty header stud broke. Luckily, it was just one stud, and it took longer to fix that than to install the headers, x-pipe system, and after-cat exhaust.