The Grand Prix GTX Ram Air was a concept car for the streets

SLP Engineering

Let’s give credit where credit’s due. Pontiac was trying really hard in the 1990s to differentiate itself from its GM stablemates, and post John DeLorean, the Pontiac division wasn’t given much in the way of flexibility and funding to make production cars with enough appeal to satisfy America’s diverse demographics. By the time SLP Engineering got its hands on the Grand Prix sedan, sales figures were far south of the Honda Accords of the world—closer to the likes of Nissan’s Altima. But then something magical happened.

Never intended for public consumption? Pontiac

Meet Pontiac’s 300 GPX concept and silently weep for its inability to make production. The supercharged 3800 V-6 made about 75 more horses than stock, along with a delightful 330 lb-ft of torque, probably thanks to a smaller supercharger pulley allowing for 10-psi of boost. These power figures are disturbingly close to the LT-1 small block Chevy of the era and were backed up by a Torsen limited-slip differential—an item almost as necessary as the 255-width tires for a front-wheel drive Poncho with this much grunt. Of course, Pontiac’s engineers tweaked the suspension and brakes to differentiate the 300 GPX from a luxury or fleet-spec Grand Prix on the showroom floor, holding it all inside, thanks to a body kit worthy of vintage wide track references (5.5 inches wider up front, 7.25 inches in the rear).

The package was wrapped up in an executive-style, quad-bucket-seat configuration with a rear console not unlike the earlier GM-10-based coupes, or the 1974 Cadillac Fleetwood Talisman. Pontiac’s family sedan was cool, even though it drove the “wrong” wheels—so cool that this 300 GPX, had it made production, coulda stolen the 2005 Chrysler 300C’s glory, elevating the General’s star-crossed GM-10 platform from wanna-be Taurus sales disappointment to a proto Chrysler LX superhero. The two even have the same number in their name!

Buick 3.8 V6 L67 Supercharged

And now imagine the 300 GPX treatment for sedans elsewhere in GM’s W-body fleet, radical takes with names like Lumina Super Sport, Buick LeSabre Ultra, and Oldsmobile Holiday 88 but I digress.

We’ve discussed SLP Engineering in the past (here and here), but now we see how their efforts make a mainstream sedan far less yawn-inducing. This is how the 300 GPX goes from Auto Show stage queen to a GTX Ram Air that’s an easily-financed mode of transportation for Middle America. Power is down from the concept, but a still-impressive 260 horsepower came from SLP’s high-flow induction and cat-back exhaust, while beefier 17-inch rubber optimizes the supercharged package.

Performance was impressive for the late-1990s, as Motorweek tested the GTX Ram Air and reached 60 mph in 7.1 seconds. A 15.3-second quarter-mile time was more than respectable back then, too. And the GTX Ram Air clearly looked the part, as the hood so closely resembled the 300 GPX concept that you’d be forgiven for postulating that SLP Engineering made it for General Motors in the first place.

But sadly, the changes are far too modest relative to what you can bolt-on elsewhere for the supercharged 3800. And that’s because of the W-body’s impressive aftermarket following, of which SLP used to support in a big way. Which is a bit tragic, much like the GTX’s Ram Air performance when viewed against today’s family appliances. Even worse, Motorweek suggests the GTX Ram Air hood/intake/exhaust/emblem/floormat package was a $2499 standalone option for any Grand Prix, even naturally aspirated examples like the one below. Oof.


Unfortunate for sure, but we know that flash sells cars better than understated assertions could ever accomplish. Ordering a handful of GTX Ram Air packages for a local Pontiac dealership’s stock was likely a great way to garner foot traffic, to move more SE-grade Pontiacs off the lot. But the GXT Ram Air (or any supercharged W-body, for that matter) needs far deeper aftermarket upgrades to truly impress, or to stay ahead of the likes of a new Nissan Leaf.

And yet something special happens when you do just that. You make that mainstream sedan (or coupe) into the vehicle that General Motors’ engineers wished they could produce if they weren’t working with one hand tied behind their backs. The original concept of the Pontiac 300 GPX that pre-dates all modified W-bodies proves it, and replicating it wouldn’t be too hard if you found one of SLP’s Ram Air Grand Prix GTXs for sale.

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    I have one of these – a 2001 with all the options and a special order color. No one seems to know what it is. So, thank you for this article!

    Laurie, always loved those cars, still search online weekly waiting for a nice low mile one to pop up for sale. What’s the details with yours? Color, miles, coupe or four door?

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