The entire installation process takes less than one hour; add some time for dial-in tuning, and you have a true afternoon bolt-on modification that really works. To check the unit out, we arranged to test it alongside the stock Mercury intake system on my personal drag hull, an Allison Super Sport SS-2000 with a mildly modified Mariner 2.5 EFI short shaft. I'd just barely broken this engine in last fall when I raced the rig in the last two New England Outboard Drag Racing Association races of 1998. The combination was competitive right from the start; in fact, I won the last race handily. In early winter, we journeyed to Jupiter in southeast Florida to test the SVS intake with Tony Brucato himself on the St. Lucie Canal. Brucato had already marked out an approximate quarter mile with his GPS on the deserted waterway, and the narrow river was ours for the day's test session.

Removal of stock air horn, ECU and reed plate was necessary to facilitate testing of bored air horn and then SVS. Entire test took only one afternoon.

Note bored-out inner diameter of modified air horn.

Removing bored air horn shows modified reed plate.

To make things a bit more interesting, we arranged to test a "bored and ported" Mercury air horn and intake spacer plate along with the SVS and stock intake. While the one-inch-thick intake spacer is available as an accessory for the 2.5 EFI from your local Mercury Racing dealer, the bored and ported intake horn is a custom item. This is a popular modification, along the lines of the "more air is better" theory. Many custom shops will port the stock air horn assembly, although experienced tuners like the Diamond boys doubt the effectiveness of this mod. Well, we'd soon find out. Our plan was simple. The stock air horn and intake manifold would be our first test. We'd make as many quarter-mile runs as I needed to get comfortable with the setup and then record the best three elapsed times and trap speeds using a digital stopwatch and Stalker radar gun. Brucato himself would man one stopwatch, while my buddy Tim Greenberg would man a second stopwatch as a backup as well as work the radar gun. We made the decision to aim the gun at the boat for a three-quarter track speed recording, as it would be impossible to accurately record the finish line trap speed unless the boat was aimed dead-on at the gun, necessitating another operator positioned beyond the end of the track.

My 2.5 Mariner had been equipped with several bolt-on hop-up items to make the rig competitive in American Power Boat Association (APBA) Super Gas class drag racing. In a nutshell, Super Gas rules call for an internally stock 2.5 EFI but allow for bolt-on hop-ups. My Mariner used 26-cc blueprinted drag heads, a custom Diamond Marine lightweight flywheel, a ported and blended Diamond drag exhaust tuner, a programmable Rapair/Mercury A6 ECU with adjustable fuel curve, ported G-Force reed cages with Mercury Racing reeds and a custom JC's Prop Shop modified gearcase. The gearing was stock 1.87:1 issue, and the propeller used during the test was a custom 14" x 24" Yamaha drag propeller worked by JC's. The manual setback plate was set at eight inches of setback, with the propeller shaft one-eighth of an inch above the pad. In race trim, this combination weighs approximately 1,475 pounds including driver. Typically, it's capable of high 11-second quarter-mile times, turning approximately 9,600 rpm at 100-plus mph.

Installing SVS was a simple operation requiring no other changes to the motor.

Red LocTite 272 was used on all bolts and nuts to ensure that none would vibrate off end up inside the Merc's powerhead.

Adjusting intake tract runner length is easy with the SVS; just add or remove the stacks.

We started the test with the stock setup. After making several runs, the best recorded passes averaged 12.45 seconds over the quarter mile, with speeds at a three-quarter track recorded at 89 mph. This was approximately five-tenths of a second off the boat's best recorded race times, due in part to the humid Florida weather and a slightly longer track. At any rate, we had a baseline, and it was time to try the next intake.

The SVS unit was next in line, and it took approximately one hour to pull the stock system off and replace it with the SVS. After fine-tuning the manifold vacuum, with Brucato making sure we didn't screw up the unit, we headed back to the track. A low-end hesitation kept quarter-mile times to the high 11-second range, but after fiddling with the vacuum port a little more, the engine came to life. The results could easily be felt as I cranked off several passes in the 11.6 second range, with a best of 11.5. The three-quarter track speed had increased an incredible nine mph, to 98. The addition of the SVS could clearly be felt, as the motor had lots more "bite" and pushed the Allison with a new, more authoritative demeanor. The boat snapped to attention and absolutely ripped through the quarter mile. Brucato and Tim noticed the change immediately from a quarter mile away as the boat charged on plane and then carried its hull more cleanly through to the end of each run. There was no question that the SVS had a drastic effect on acceleration.

The finished install not only shaved seven-eights of a second off the boat's quarter-mile times, but it looks awesome as well.

Last up was the ported and bored Merc air horn. We installed this unit with the one-inch intake spacer, said by Merc engineers to significantly increase acceleration response. This took a bit more time, but we were back on the water before darkness began to fall. Unfortunately, performance remained virtually the same as with the stock setup. Quarter-mile times were higher, with an average of 12.54 seconds (an increase of about one-tenth of a second over the stock intake!). Trap speeds at the three-quarter track stayed steady at 89 mph. I felt no appreciable difference from the driver's seat, and Tim and Tony noted that after seeing its previous performance with the SVS, the boat now almost seemed sluggish off the line and did not carry as well at the finish line.

In this test, the SVS was clearly the intake of choice.

For those looking for a significant per formance increase, the SVS is an excellent investment. At $1,795, it's not cheap, but you get more than what you pay for. This unit is a well-designed, well-machined piece that really wakes up Mercury's 2.5 EFI. If you have average to good mechanical skills, you can install it in your driveway in an afternoon. Brucato's customer service is excellent, as this is the only product he makes and therefore backs it up with great tech support. Merc 280 HP 2.5 owners can rejoice -this unit will work on the new motor. Pro Max and stock three- liter owners can take advantage of SVS technology too, as Brucato makes two models that work very well on these two engines. For Mercury performance buffs, the SVS is a bolt-on that's worth looking into.