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Tech Review—UPR Products Pro Series Insane Horsepower Kit


By Michael Galimi

Photos by Race Pages

In the mid-to-late 1990s there was an 8-second True Street car running under the UPR Products banner that flat dominated the street race Mustangs of the time. The talented Willie Figueroa was the pilot for the team’s Vortech-supercharged 1995 Mustang GTS, winning multiple World Ford Challenge and NMRA Wild Street competitions. The street car ran 8.40s and would eventually become one of the poster cars for BFGoodrich as it advertised the newest craze in DOT tire racing—drag radials! As many people focused on the car’s ability to run in the 8s and still have street manners, Joe and Mark Mainiero and their staff were using the car as a test-bed for its new line of Pro Series suspension components.

Fast-forward nearly 20 years later and UPR Products has become one of the household names for Mustang suspension systems on the street and at the drag strip. The Pro Series suspension systems have helped Mustang enthusiasts hook better, run faster and even win championships and set records. Residing in the Pro Series line-up is the Insane Horsepower kit, designed for 1979 through 2004 Mustangs, and the kit includes two components to help in extreme conditions—the Wishbone Rear-End Locator and XD Anti-Roll Bar.

The XD Anti-Roll Bar, sometimes referred to as the double anti-roll bar, features four arms on a single bar. The purpose of the extra arms is to help distribute the load and add to the longevity of the end links.

Each component, on its own, offers a specific and useful purpose in any big power application. “I usually recommend the double anti-roll bar for anything above 1,000hp or pulling sixty-foot times in the 1.20 range or quicker,” was the comment from Sharad Raldiris of UPR Products. He continued, “The wishbone is more applicable when a car is running heim ends on both ends of all four control arms.” According to Raldiris, the wishbone works in conjunction with the triangulated angles of the arms to laterally locate the rear-end. The rough estimate for a wishbone is suggested at roughly 1,000hp, maybe 1,200hp depending on the application. Available for both the 8.8-inch and 9-inch housings, the Pro Series wishbone uses CNC-machined tube ends and is made from 4130 chromoly. The single heim-joint side mounts to the bottom of the rear-end housing while the other ends are welded to the frame.

When used as a complete kit, the Pro Series setup has helped push David Pearson’s “Lil Evil” Mustang to a best of 4.10 at 175 mph while using a set of Mickey Thompson ET Radial Pro 275 tires. The low 4-second performances come courtesy of sixty-foot times as quick as 1.01 seconds! It is through working with racers like Pearson, and many others on a weekly basis, that the durability and effectiveness of the Pro Series line of products are proven.

The Pro Series Wishbone feature a slip joint on one side that attaches to the rear-end housing via a heim joint. The other side has two heim ends, which are used to attach the wishbone to a pair of brackets mounted on the frame.

The benefits of a drag race spec anti-roll bar are well known. It helps eliminate the common twist that happens on hard drag racing launches. As the axle twists up, the driver’s side body separates away from the tire and creates that unique body rotation. To remedy the problem, several suspension manufacturers offer anti-roll bars and UPR offers several styles for use with and without tailpipes and in double arm designs. The XD Anti-Roll Bar features two arms on each side of the bar, often called the double anti-roll bar. The bar itself is the same between the single and double anti-roll bar kits, offering the same torsional rigidity. The extra set of arms and links helps distribute load, effectively cutting the load on each arm in half when compared to a single setup, which improves longevity.

UPR Products does recommend removing the links for street driving but if you talk to several high-profile True Street racers, they will tell you otherwise. The biggest challenge for street-use is uneven pavement, like when making a turn and the grade increases. The extra stress on the links and arms as the rear end is trying pivot will snap one or both of those components. But if driven with care and consideration, the Pro Series anti-roll bar can live on the street, just don’t tell them we told you so.

UPR Products has several packages available that include these components or each sold individually, allowing enthusiasts to upgrade as time marches on and their Mustang gets quicker and faster.


UPR Products


“Lil Evil” is one of the baddest cars on 275 radial tires having carded 1.01 sixty-foot times and a best of 4.10 at 175 mph.

Mike Galimi
Mike Galimi is the Director of Content & Marketing at ProMedia Publishing and Events with nearly 20 years of experience in motorsport writing and photography.