I don't think it would be possible to determine which is the most popular modification for C5s--custom and/or chrome plated wheels, custom cat-back exhaust systems, or high-flow induction setups. Wheels and exhaust systems are pretty much immediately noticeable. Exhausts, in addition to making LS1-powered C5s sound like the supercar they are, do add a modest amount to the power output of stock or close-to-stock Corvettes. However, the factory exhaust system, while boringly quiet, and through 2000 (with small, black quad tips), equally boring to look at, is quite efficient.
By contrast, the OEM induction system is fairly restrictive and nearly any change will yield perceptible improvements. Custom air inlet components run the gamut from higher-flow stock replacement filter elements that fit within the stock airbox to all manner of single and multiple inlet setups, custom airboxes, "power ducts" that replace the stock air bridge, and cold air/ram air systems. And that doesn't even include all the various larger-bore mass airflow sensors, ported MAS housings, and bigger inside diameter throttle bodies--the material for another, totally separate article or two.
One of the more intriguing induction setups we've seen--or at least heard about--is Vararam Industries' VR-1B ram air system. The ads (including in this publication) make some impressive claims, like 1/2-second elapsed time reductions and 5-mph increases on otherwise stock C5 in the quarter-mile. The system is unique in that it takes full advantage of the faux openings in the front fascia that house only the foglamps and waste some prime frontal real estate for a pair of drag-creating recesses by converting the dummy openings into fully functional air inlets that feed directly into a high-flow air filter and onward to the mass airflow sensor, throttle body, and engine.
In addition to the performance claims, Vararam avers that the their system is a true bolt-on, with no cutting, chopping, or drilling required, and that it does not interfere with the factory fog lamps or their function. The downside to this setup, at least as we see it, is the same thing that purportedly makes the VR-1B an outstanding performer--it is a sealed induction system that picks up all of its air from a pair of fairly low points right on the front end of the car, right out there where it can pick up water in heavy rains and even minor flooding. The ducts are formed to aim downward into troughs with small drain holes before pointing up to the custom air filter housing, but we wouldn't want to chance it in any sort of heavy downpour. That's our only caveat, and it shouldn't cause any sort of problem or inconvenience for anyone fortunate enough to have a C5 for a fair weather car--and we know just such a guy.
Tony Correia owns a '99 six-speed convertible, the same car that has appeared twice in recent issues: First when Tony installed a Hurst shifter, then when he made one of the simplest and most significant improvements any six-speed owner can by fitting it with a skip-shift eliminator. Otherwise, with the sole exception of a pair of Flowmaster "premium mufflers" (which have a really great musclecar sound), the 19,000-mile-old Corvette was absolutely stock. Tony uses a ratted out, decade-old Jeep Wagoneer for daily driving duties, and the '99 shares garage space with a retro/nostalgia-style '32 highboy roadster, so rainy day driving (yes, we do have those once in a while in Southern California) was not a major concern. Ol' Tony had the hots for trying a VR-1B, so we made arrangements to use his '99 as a guinea pig and to do both an installation and a series of before and after dyno tests on the Dynojet 248 C in the Primedia Tech Center. We also planned on conducting a series of 0-60 runs on a local, relatively unused industrial street to garner some sort of idea of real world gains from the ram air setup. (Quarter-mile tests would've been much more fun and more informative, but the dearth of decent and accessible dragstrips in the Los Angeles/Orange County metropolitan area makes testing at a real dragstrip a hit or miss proposition.) We're certain that full quarter-mile runs and some way, short of having access to a wind tunnel for the dyno pulls, to simulate the air rushing into the system at speed would've yielded some extremely impressive results, based on what we did record (see chart).
Installing a Vararam VR-1B is not particularly difficult and doesn't require a huge selection of tools. The installer will, however, need to work both beneath the front of the car and within the forward portions of the engine compartment from the top side, so having access to the Tech Center's lift made the job much easier for the center's manager, Dominic Conti.
We did our 0-60 tests with two people on board and used a Tesla Electronics "G-Tech Pro" accelerometer to measure our times. We got our best results, both before and after, with the traction control set on "Competition Driving" (which allows modest wheelspin without activating the traction control) and launching at around 1,200 rpm while slipping the clutch as we went to wide open throttle. Anything more than that, with the stock run-flats on a city street, would blow the tires away. We conducted the "before" tests just prior to installing the VR-1B. We deferred the "after" portions for several days since Vararam's instructions state that it'll take the C5's ECM 30-45 miles of sustained highway speed driving or 3-4 quarter-mile passes for the computer to adjust itself to the new, greater volume of airflow. However, the dyno results are corrected numbers, calibrated by the Dynojet's computer to compensate for variances in temperature, barometric pressure, and humidity, and our 0-60 tests were run on the same street, at roughly the same times of day, and the temperatures were very similar both days.
Remember, all of the above horsepower and torque numbers are measured at the rear wheels--in other words the power that is actually reaching the pavement. Conservatively, you will see a power loss of at least 15 percent between "crankshaft" or "flywheel" output and rear wheel power as the horsepower and torque work their way from the engine through the clutch, torque tube, transmission, differential, halfshafts and U-joints, and the hubs, wheel bearings, and rear brakes before ever getting near the tires and pavement. We picked up 11.9 rear wheel horsepower and 11.2 rear wheel lb-ft of torque with the car sitting still on the dyno, and netted a 0.46 second improvement in 0-60 acceleration. The horsepower and torque gains came on around 2,250 rpm and never dropped off. The improvement in acceleration is especially noticeable when you're rolling along the freeway at 70-80, pull the tranny back into Third from Overdrive and hammer it for a few seconds.
To sum it up, we'd have to say that the Vararam VR-1B works as claimed-the installation was straightforward, the quality of the components is good, everything fit, nothing had to be cut, and most important, the car hauls! It's nice when we get to test parts that do everything they're supposed to.