Shierts' fire-breathing Hayabusa dragbike has too many mods to list, so we'll just list his parts sponsors: APE (American Performance Engineering), Dynojet, Falicon Crankshafts, JE Pistons, Millenium Technologies, Orient Express, Webcams Inc., Performance Cryogenics, Nutec Racing Fuels, Trackside Racing Supply of Canton, Gold Star Lazer Chain Guards and Zero Gravity. Shierts was planning on getting me into the 8.5-second quarter-mile range with this bike, but a fried clutch and lack of time killed those plans.

The Stage 4 takes that to the next level by replacing both cams with Shierts' special grind, 1mm oversize valves with matching spring assemblies (plus porting to work with those valves), a set of 2mm oversize JE pistons machined to Shierts' specs with matched cylinder assembly, plus a thorough R&R of the complete motor to ensure that everything goes and works together smoothly. And how much horsepower do you get for your $5545? I watched as Shierts' own GSX-R cranked out 193 horsepower, with a nice, linear power curve. Then I watched in amazement as his customer's bike (belonging to Joe Bidwell) was strapped to the dyno, then promptly proceeded to pump out 197 horsepower at 11,250 rpm, with 100 ft./lbs. of torque! Definitely impressive for a pair of normally aspirated GSX-R1000s.

A customer's bike more powerful than the shop owner's machine? One difference was the new carbon airbox that Shierts is now marketing. The comparatively small stock airbox is jettisoned, and Shierts' piece basically form fits around the entire area underneath the fuel tank just above the throttle bodies, and uses a rubber seal against the tank to form the airbox "lid." "I used his bike to mold the new prototype, so I didn't have a chance to make a production unit for mine," explained Shierts. "It really doesn't do anything on top, but there are really big gains in the midrange-at least 10 to 13 horsepower."

It was somewhat difficult switching from bike to bike during my dragstrip runs. Here Shierts gives me some tips to help out on the turbo 'Busa (right). Shierts' carbon-fiber airbox provides huge improvements to a highly-modified GSX-R1000's power curve, with at least 10-13 horsepower in the midrange (left).

What was even more impressive was riding the GSX-Rs on the street. Although both bikes were fitted with Coby Adams swingarms that allow length adjustability to 65-inch wheelbases for dragracing, Bidwell's bike was at near-stock wheelbase, so it handled practically like a stocker. And that allowed me to enjoy what was probably the most incredibly fun powerplant I've ever had the chance to play with on the street. Throttle response just off idle was a bit fluffy, but anything above 2500 rpm, and the GSX-R was as crisp as stock. And once the tach needle swung past 4000 rpm, there was so much power and torque available that you felt as if there was a supercharger attached to the motor. Smooth, linear, controllable power that made third gear, 100 mph wheelies just a roll-on away, transforming into a fearsome top-end rush that immediately made me wish there was a roadrace track nearby.

Shierts even arranged for me to ride one of his customers' GSX-Rs to show that he sells what he races. There's no doubt that Joe Bidwell probably has the strongest GSX-R in all of Kansas; with 197 horsepower, his bike even bested Shierts' personal GSX-R.

We immediately segued to the quarter-mile strip at Darlington Dragway in South Carolina the next morning to see what these bikes could do. As usual, scheduling and other logistical problems meant that I had a limited amount of time to sample all four bikes and try to get some decent runs out of them. The fact that each bike was a power monster with its own distinct personality made things that much tougher.

After a few tries on Bidwell's GSX-R with the stock setup (not lowered, near-stock wheelbase), I realized that it would be practically impossible to get it anywhere near low nine-second times; the bike's short wheelbase and high center of gravity conspired to have the front end pointing out cloud formations at nearly anything over half-throttle in the first two gears, killing the first 60 feet of the run. With my best run way up in the 9.78 second range, Shierts took Bidwell's bike and lowered the suspension, while I acquainted myself with Shierts' own GSX-R.

It was interesting to note the slight difference in personalities between the two bikes, even though their modifications were identical-save for the carbon airbox on Bidwell's bike, which is what made his GSX-R feel just a tad snappier than Shierts' machine. Still, with the chassis lowered, and wheelbase lengthened a bit (but nowhere near the full 63-plus inch extension possible), Shierts' bike launched much better off the line. I immediately dropped my times down to low nines, with a best of 9.25 at 154.12 mph.