“This email is surprisingly not being sent from inside a jail,” began Bradley’s report on riding our project Suzuki GSX1250FA for the first time. “Man, that thing is strong.” Backing up a few months, we had found the GSX to be somewhat anemic in our comparison test with the Kawasaki Ninja 1000 and Yamaha FZ1 (“Battle of the Super-Standards”, Aug. ‘11). Plenty comfortable for commuting, the heavy Suzuki simply ran out of steam at the top end, to the tune of more than 25 horsepower compared with the Ninja and FZ1. Kento and Bradley were using the GSX for the daily freeway grind and not much else, and that should have been the end of the story…until a reader commented that Dale Walker from Holeshot Performance had a combination of parts that more than made up that horsepower difference with little effort.
Intrigued, we contacted the company, ordered up a “Stage 2” kit and set to work. Walker is a former Top Fuel drag racer and no stranger to the magazine, having been involved in several projects over the years. His Holeshot company offers hop-up parts for various models, but the Bandit (the GSX’s former name) seems to be an ongoing pet project. Central to the kit is Holeshot’s stainless steel 4-into-2-into-1 exhaust system, which consists of a beautifully polished and tig-welded header matched to the company’s stainless steel mid-pipe and muffler. The header retails for $675, while we opted for the 14-inch, satin-black Comp 2 slip-on ($415). The slip-on is also available in a 17-inch length, a “super-stealth street core”, and with a polished outer skin. The system mounted up easily enough in a couple of hours, and shed 20 pounds from the Suzuki. The lower fairings needed to be trimmed at the leading edge to clear the header pipe, but there is plenty of room to keep the stock centerstand if you choose.
The stainless steel header...
The stainless steel header system and black-anodized slip-on are works of art, and the exhaust mounted up easily. The GSX’s lower fairings had to be trimmed to clear the header, but some nice work by our shop foreman Michael Candreia made the job look completely factory. The Bandit and GSF models—even though the fairings are different—will need their lowers similarly trimmed to fit.
Only the Holeshot Performance...
Only the Holeshot Performance exhaust gives any exterior hint of our GSX1250FA's modifications; you wouldn't know power has been increased by a whopping 30 percent just by looking at the bike.
We spooned on a set of Michelin’s...
We spooned on a set of Michelin’s new sport-touring tires, the Pilot Road 3. They offer much more linear steering characteristics compared with the OEM-spec Bridgestone tires, in addition to better grip. With time we’ll be able to fully test the company’s claims of wet-weather performance and increased mileage.
We installed a K&N filter...
We installed a K&N filter and trimmed the airbox lid as per Holeshot instructions. The modification opens the entire face of the filter to the atmosphere, significantly improving breathing.
On the opposite side of the engine, we removed the secondary butterflies from the GSX’s SDTV throttle bodies, which required an afternoon’s work. Throttle bodies on the bench, it’s a simple matter to remove the two screws holding each butterfly to the rod running through; we used a hair dryer to loosen the thread locking compound on the screws, easing things considerably. A K&N air filter ($49) was slipped into the Suzuki’s airbox, and the lid modified per Walker’s instructions. This consisted of cutting out the entire lid save for the mounting screws and flange to actually hold the filter in place. A Dobeck Performance TFI tuning box ($257) was installed and set, again according to Walker’s instructions. The TFI box, which uses potentiometers to adjust fueling in low-, medium- and high-rpm ranges, works well with the GSX and these modifications. According to Walker, there is no need for anything more elaborate (or expensive!). Finally, we disabled the Suzuki’s O2 exhaust sensor with a bypass module ($15). All these parts — the air filter, TFI box and bypass module — are available through Holeshot Performance.
The Dobeck Performance TFI...
The Dobeck Performance TFI box taps into the bike’s fuel injection harness and adds fuel in three rpm ranges based on potentiometer adjustments. The unit provided plenty of adjustment to match the GSX’s modifications, with excellent air/fuel readings on our dyno and smooth-running performance on the road.
Key to the performance increase...
Key to the performance increase is the removal of the secondary butterflies from the Suzuki’s throttle valves. Two screws hold each butterfly plate to the actuation rod; we used a hair dryer to loosen the thread locking compound, and had the job completed in just a few minutes once the throttle bodies were off the bike.
This Holeshot fork brace is...
This Holeshot fork brace is nicely crafted from billet aluminum and stiffens the Suzuki’s conventional fork, which—even at 43mm in diameter—is a bit spindly for the stock bike’s 567-pound curb weight. Inside the fork tubes are Cogent Dynamics springs and Race Tech Gold Valves. We sourced the springs from Holeshot, while Race Tech performed the installation.
We had our doubts when a reader...
We had our doubts when a reader first told us of the Holeshot upgrades for the GSF/Bandit/GSX series, but here is the proof: A whopping 27-horsepower increase, all with just a few bolt-on parts and minor mods.
As you can see from the dyno chart, our GSX has been completely transformed. Torque is up by 13 ft-lb, while power has increased by a whopping 27 horsepower — an incredible gain, all for about $1400 and a weekend’s work. We stopped Bradley drooling enough to get more details out of him: “Tons of top-end power, and it still has that extremely smooth delivery I loved about the bike in stock trim. The bike has a bunch of power down low too, although the midrange is just OK. Accelerate hard off the line, grab a gear and it even wants to screech the (OE) tires! Biggest difference is past about 7000 rpm. It just pulls extremely hard all the way up to the rev limiter, with absolutely no indication that it wants to slow down. You can hardly feel the dip in power that the dyno figures show either. It’s still great on the freeway, with very little vibration. The one thing I noticed, though, is that the on/off throttle transition is a little abrupt (which if I remember correctly, was a problem we experienced with the bike in stock trim). Other than that I am damn impressed. Tons of power that is delivered in an extremely smooth, crisp manner; I have few complaints.”
Kent concurred, and the midrange lull that gives the dyno chart an odd shape has us mystified. Walker reports he has conducted hours of tuning and investigated other forms of EFI management in an effort to smooth out the curve, to no avail. Note that the stock bike’s curves also show a healthy bump right at the top-end, and we’ll surmise that it’s an ignition-related characteristic. Even with that oddity, the bike is heaps of fun to ride and the powerband is plenty smooth for the type of riding the bike is used for.