It has been dubbed by many as a mini-LS7, and for good reason. Bone stock, our '09 C6 tester made a whopping 406 rwhp on Redline Motorsports' Dyno Dynamics rollers. With a big cam, Kooks 1 7/8-inch long tube headers, Borla exhaust, VaraRam cold air intake and custom tune, output jumped to 483 rwhp, not to mention well over 400 lb-ft of torque. We couldn't help but wonder what the LS3 would be capable of with a good set of CNC-ported stock heads. Thankfully West Coast Cylinder Heads was more than happy to comply with our wishes, as they have been running a well-planned CNC program on the identical L92 heads for over a year now. With these bad boys we were confident Redline tech Jon Bettini's C6 would hit 500 ponies. Follow along as GMHTP makes another trip up to Redline's pristine Schenectady, NY shop.
| FLOW (CFM)* |
| INCH LIFT | INTAKE | EXHAUST |
| .100 | 75.5 | 63.1 |
| .200 | 160.1 | 117.0 |
| .300 | 224.2 | 181.9 |
| .400 | 275.1 | 212.6 |
| .500 | 307.7 | 231.7 |
| .600 | 343.9 | 242.6 |
| .700 | 355.1 | 248.4 |
| *Flow tested at 28-inches of water using a 4.030-inch bore |
 West Coast Cylinder Heads...  West Coast Cylinder Heads LS3/L92 Stage 2 CNC program takes the intake runners out to 268 cc, the exhaust is opened to 99 cc, and the combustion chambers are cut to 75 cc (though on this build they were cut to 66 cc for an 11.52:1 compression with the stock bottom end). As good as the stock heads flow, it is easy to find its limits with a well-matched cam. I'll let the flow numbers speak for themselves, and say only that a rectangular port is definitely the way to go. The high lift numbers look like something you'd use on a high dollar race build, not a $1,880 street head. |  The assembled heads come with...  The assembled heads come with REV lightweight stainless steel 2.16 intake and 1.60 exhaust valves... |  ...Patriot Extreme dual springs...  ...Patriot Extreme dual springs are good for up to .650-inch lift and provide about 155 lb. on the seat and 375 lb. of open pressure... |
 ...A titanium retainer is...  ...A titanium retainer is used along with a Super 7 valve lock and Viton seals. West Coast says these high-flowing heads can easily make 640 hp with a 402, however the factory intake manifold severely limits its potential. |  Redline's hulking tech Jon...  Redline's hulking tech Jon Bettini owns our murdered-out '09 C6 test car, which prior to the head swap was sporting Kooks long tube headers, X-pipe with high flow cats, Borla catback, VaraRam cold air intake, and a real lumpy cam. The healthy hydraulic roller measures 239/247-duration, .623/.623-inch lift, and 115LSA with 3-degrees of advance. This combo took the LS3 from 406 rwhp (stock) to a shocking 482. A peak at the EFILive datalogue from the dyno pull seemed to indicate the custom tune was spot on. |  Redline proprietor Howard...  Redline proprietor Howard Tanner starts the head swap by removing the coil packs as the radiator is emptying into a bucket below. |