Early adopters of the C5 in 1997 will remember. Those of you who drove your shiny new coupe off the dealer lot and directly into the staging lanes at the local dragstrip no doubt recall the novelty that was the all-new LS1 engine. Mid-to-low-13-second elapsed times were plenty quick back in the day, and the old-school guys certainly took notice. Do any of these backhanded compliments and gems of enlightened opinion ring a bell?

"Yeah, cool, but those engines won't last."

"Sure, it's quick. For what it is."

"That's as fast as they'll ever go."

"I'd rather push my big-block than drive one of those. " (OK, I made the last one up, but you just know some ignoramus somewhere said something to the effect.)

We all know now that those first LS1s were just the tip of the iceberg. In less than two years, those mighty little 346s were commonly turning mid-11s at nearly 120 mph, with little more than some rudimentary head porting, a cam swap, and some headers. Hit 'em with a shot of nitrous and bang! You were in the 10s. Not bad for what was dismissed as a novelty engine just several months before.

As the LS1 pioneers continued to identify and work around each successive performance bottleneck (remember the excitement around the LS6 manifold?), a subtle shift in attitude began. Slowly but surely, mainstream performance enthusiasts begin to take notice of the LS-series engines. No longer was the LS1 the engine of choice only for Corvette and F-body guys. It began showing up in high-end street rods and even some boutiquey muscle-car restifications.

Now, 12 years on, there are LS-series powered cars running in the 7s. There are nearly a dozen choices in aftermarket cylinder heads. There are even a small number of aftermarket aluminum and cast-iron blocks. Want a turbo or supercharger to strap on that mill? No problem; there are oodles of choices. Arguably, no family of engines before or since has enjoyed such spirited development from the aftermarket.

Among those throwing their hat in the ring is none other than Trick Flow Specialties (TFS). Long known for its small-block-Ford cylinder heads, which were at the forefront of the 5-liter-Mustang revolution of the 1990s, TFS has broadened its offerings with cylinder heads for big- and small-block Chevys and, notably, the LS-series engines.

TFS' GenX series of cylinder heads represents the Ohio company's first foray into the LS-series arena. Offered in five versions, there's a GenX head to fit just about any conceivable application. Each version is available fully assembled with stainless-steel valves, 1.300-inch dual valve springs rated at 0.650-inch of maximum lift, 7-degree titanium spring retainers with machine-steel locks, Viton valve seals, and hardened valve springs. The heads are also available as bare castings with just seals and guides. Best of all, TFS heads are made in the USA.

As Cast
For stock or moderately modified LS1 and LS2 engines being built with one eye on the budget, TFS offers its GenX as-cast heads. Though less costly, the as-cast heads benefit from all the same features as the high-end CNC-ported units. Trick Flow's first order of business was to design and cast an ultra-rigid structure that minimizes flex for improved head-gasket sealing, even when subjected to the extraordinarily high cylinder pressures often seen with boost or nitrous.