Dale Amy
August 27, 2013

Huh? What was that? The white Shelby rumbling past in downtown Sturgis, South Dakota, looked passably stock at first glance, but it wore these enormous rear rims and skins—and offered up a broad booty view that would make the likes of Kim Kardashian seem positively scrawny by comparison. We're talkin' bountiful. Yet, nothing looked tacked on or out of proportion, so we figured a little further investigation was mandatory.

When we caught up with Dan Stahlman, the coupe's owner told us that his '07 GT500's 6-inch rear-body widening had been hand-fabricated, and done mostly so he could mount up the type of fat rear rubber he'd become accustomed to when he previously owned a Dodge Viper GTS coupe (seems he has a thing for snakes…). As if that weren't enough, Dan then casually mentioned that his KR800 had run 10.18 seconds at 138 mph in the quarter and had 202 mph in the 2009 Texas Mile top-speed competition. That's when I headed for my camera bag…

Some of you may be as surprised as I to learn that such performance—especially the berserk 200-plus velocity—was achieved with no more underhood mods than the simple substitution of a Whipple 3.4-liter twin-screw blower in place of the factory Roots. Mind you, the big Whipple does blow forth sufficient boost for around 755 rwhp from Stahlman's otherwise stock Condor 5.4-liter while on pump gas, or over a thousand ponies at the wheels when Triangle Speed Shop's specific tune for C16 race fuel is programmed in. Triangle (in Orange, Texas) gets full credit for installing the polished Whipple and developing those race- and pump-gas tunes for the crazy-fast coupe.

For its assault on the Texas Mile—basically a standing-start, one-mile top-speed competition staged on an old military runway—the big-butt Shelby also received revised close-ratio gearing within its factory Tremec TR-6060 transmission housing, in order to keep the engine tightly within its most potent power band during upshifts (goodbye overdrive.) Naturally a Maximum Motorsports rollcage was also part of the makeover, as was lowering ride height, but no particular efforts were made to smooth the Shelby's somewhat blunt aerodynamic characteristics—that is to say, blunt compared to the Corvettes, Ferraris, and Ford GT supercars that frequent the top-speed competition. To competitively tear that kind of hole through the atmosphere, this thing is obviously generating some intense power, yet Dan street-drives it as often as possible when not attending to his honey bees (he owns Stahlman Apiaries, in Selby, South Dakota.) Is his 200-mph KR800 sufficiently well-behaved for such street duty? Dan says it's ideal for taking his "favorite girl for a steak or lobster 200 miles away on a Saturday night." So, yeah, it's civilized.

Getting back to the body mods, it's worth repeating that the rear widening was accomplished not with any sort of kit, but rather the old-fashioned way, with precise measurement and the obviously well-honed metal/bodywork skills of he and his buddy Andy House (who owns Performance Auto in Lufkin, Texas). It was, in other words, a custom fabrication. A look at our images should confirm that these guys did a masterful job of widening this Snake's tail—including its fenders/quarters, rear fascia, and underbody diffuser—to provide that generous rubber room, all without throwing the Shelby's overall styling out of whack. The choice of staggered-size CCW SP20 rims was a subtle touch as well. These bear passing resemblance to stock GT500 hoops, yet that generous lip on the 13.5-inch-wide hind pair gives clear evidence of the coupe's added rear girth. And grip.

And if you're wondering why a guy from South Dakota would have most of his mods done way down in Southeast Texas, it's partly because Dan pretty much transfers his whole beekeeping operation south for six months every winter—giving him that much more time to enjoy pedaling his KR800, while also bringing him closer to the Texas Mile competition, which—we kid you not,—takes place in Beeville, Texas. Must be a hive of activity…

Horse Sense: Fitting the sizeable Whipple 3.4-liter blower under a stock GT500 hood is a problem—unless you order Whipple/JDM's K-member spacer kit.

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5.0 Tech Specs

Engine and Drivetrain


Block
Aluminum 5.4-liter
Crankshaft
Forged steel
Rods
Cracked forged-steel I-beams
Pistons
Forged aluminum
Camshafts
Dual overhead
Cylinder heads
Aluminum four-valves per cylinder
Intake manifold
Cast-aluminum w/ air-to-water intercooler
Power Adder
Whipple 3.4-liter (W210HPR) twin screw, 22 psi
Fuel system
Dual pumps w/ Fore Precision rails, and 80-lb/hr injectors
Exhaust
American Racing long-tube headers w/ 3-in stainless exhaust
Transmission
Tremec TR-6060 w/ modified gear ratios
Rearend
8.8-in w/ 3.55 gears, and 31-spline axles

Electronics


Engine management
Copperhead PCM w/ Triangle Speed Shop tune
Ignition
Stock coil-on-plug
Gauges
Auto Meter fuel pressure and boost

Suspension and Chassis


Front suspension
K-member
BMR Fabrication
A-arms
BMR Fabrication
Struts
Stock
Springs
Eibach
Brakes
Brembo 14-inch-diameter vented discs w/ four-piston aluminum calipers
Wheels
CCW, 18x8.5-in
Tires
Goodyear F1, 275/35R18
Rear suspension
Shocks

Eibach
Springs
Eibach
Control Arms
BMR Fabrication
Brakes
11.8-inch-diameter vented discs w/ two-piston calipers
Wheels
CCW, 19x13.5-in
Tires
Nitto NT-05R Drag Radial, 345/30R-19

The math is apparently simple: one Whipple 3.4-liter twin-screw plus a pair of American Racing long-tubes equals 755 rwhp on pump gas and somewhere north of 1,000 on C16. This is on an otherwise-stock 5.4-liter long-block that has survived 200-mph runs, 10-second passes, and lots of street antics.