650 HP Shelby GT500 Mustang vs 556 HP CTS-V Drag Race Video – Heads Up – Road Test TV

A 2008 Shelby GT500 running a smaller supercharger pulley, a custom tune, and drag radials for roughly 650 horsepower takes on a completely stock 2013 Cadillac CTS-V Coupe and its factory 556 horsepower LSA V8 in a heads-up quarter mile. The Cadillac’s showing against a 100 horsepower deficit drew real respect in the comments, and the channel even responded to a viewer’s question about the included density altitude data. Watch the run to see just how close a modified car and a stock one can actually be.

Heads-up drag racing has one rule that makes it different from every other format: both cars leave the line at exactly the same time, no handicap, no breakout, nothing but raw performance deciding who gets to the stripe first. That rule turns this particular race into an uneven fight on paper before either driver even stages, one car carrying a serious horsepower advantage from aftermarket modifications, the other running completely stock from the factory floor. What actually happens between the line and the traps is the reason this video keeps drawing new viewers years after it was filmed.

Heads-Up Racing Leaves No Room for Excuses

The modified car in this heads-up pass is a 2008 Shelby GT500 Mustang, built with a smaller aftermarket pulley to spin its factory supercharger faster, a custom tune to match the added boost, an upgraded exhaust system to help the engine breathe, and drag radial tires to put the extra power to the ground. Combined, those modifications push the GT500’s supercharged 5.4 liter V8 up to roughly 650 horsepower at the crank, a meaningful jump over its factory rating.

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What the GT500’s Modifications Actually Added

Its opponent is a 2013 Cadillac CTS-V Coupe, running completely bone stock with no modifications of any kind, powered by the LSA 6.2 liter supercharged V8 that GM also used in the Camaro ZL1, factory-rated at 556 horsepower. On paper, giving up roughly 100 horsepower to a heads-up opponent in a straight-line race should not be a close fight, and most viewers going in likely expected exactly that.

A Stock Cadillac Against a 100 Horsepower Deficit

The CTS-V’s performance against that deficit drew genuine respect in the comments, with viewers repeatedly calling out just how impressive a fully stock car’s showing was against a purpose-modified competitor. One commenter put it plainly, saying that giving up 100 horsepower and still running the numbers this Cadillac ran was nothing to scoff at, a sentiment echoed by several others who said the result changed how seriously they took the CTS-V as a factory performance car. That kind of direct back-and-forth between a channel and its audience is rare on YouTube generally, and it builds a level of trust that a video with no creator engagement at all simply cannot replicate, especially in a niche where viewers are often more knowledgeable about the specific hardware than the person filming.

Why the CTS-V Earned Real Respect

Road Test TV itself engaged directly with the comment section on this video in a way that added real credibility to the numbers on screen, responding to a viewer’s question by confirming the channel tries to post as much relevant data as possible on future test runs, including conditions that affect performance. One viewer specifically praised the inclusion of a density altitude reading alongside the run, a detail that matters enormously for anyone trying to compare quarter-mile times across different tracks, elevations, and weather conditions, and one that a lot of amateur drag videos simply leave out.

Road Test TV Weighs In on Its Own Data

That level of technical transparency is part of what separates a channel like this one from casual smartphone-filmed street races. Density altitude accounts for temperature, barometric pressure, and humidity all combined into a single figure that directly affects how much power a naturally aspirated or even a supercharged engine can actually make on a given day, which means two runs recorded under different conditions are not always a fair apples-to-apples comparison unless that data is included alongside the elapsed time.

Why Density Altitude Actually Matters

Several commenters used the video as an opportunity to compare notes on their own builds, with one viewer noting they were running the exact same pulley and tune combination in their own GT500 in the same color, and that watching this race pushed them to finally get their own car to the track. That kind of direct, build-specific engagement in the comments is common across this channel’s catalog, and it points to an audience that is not just watching passively but actively cross-referencing their own cars against what they see on screen.

Viewers Comparing Their Own Builds

The Shelby GT500’s supercharged platform has long been a favorite among tuners specifically because of how responsive it is to exactly the kind of bolt-on modifications used in this race. A smaller supercharger pulley is one of the simplest, most cost-effective ways to add real power to these cars, since it requires no internal engine work, just a component swap and a supporting tune to keep the air-fuel ratio and timing safe under the added boost. The GT500’s factory supercharger, an Eaton unit shared across several Ford performance applications of that era, was specifically engineered with enough headroom built in to handle exactly this kind of pulley-and-tune upgrade without requiring the internal engine work that more aggressive power adders would demand.

Why Tuners Love the GT500 Platform

The CTS-V, by contrast, represented Cadillac’s most serious attempt yet at building a genuine performance sedan and coupe capable of embarrassing dedicated sports cars, and the LSA engine under its hood shared its fundamental architecture with engines found in some of GM’s most respected performance nameplates. Watching it hold its own against a heavily modified GT500, in a heads-up format with no handicap to lean on, is exactly the kind of real-world proof that spec sheet comparisons alone rarely deliver. That shared LSA architecture is part of why the CTS-V holds a special place among GM performance fans even today, a genuine four-door and coupe alternative to the Camaro that never sacrificed the underlying hardware to get there.

What This Race Actually Proves

Watch the full run to see exactly how close the gap actually was between a fully built GT500 and a stock CTS-V, and pay attention to the density altitude reading Road Test TV included, since it is the detail that turns this from a simple race video into something closer to a legitimate data point for anyone comparing these two platforms.

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