RHS [1] has added to their Pro Elite line with these new 307cc cylinder heads. Designed for the ever popular big cube LS builds that are so popular right now, these heads can perform well on performance street engines, and even smaller cubic inch race engines.
Official Release:
Big engines make big power, but often cylinder heads don’t provide the necessary flow characteristics for large power plants. New RHS Pro Elite LS7 Big Port Cylinder Heads solve this problem. 
[2]
They are the only raised runner aftermarket LS7 heads with the runner volume to support large cubic inch applications, yet they are still able to utilize both production and aftermarket intake manifolds and valve trains. The heads work well with all existing LS7 parts, but have a bigger intake port size and valve than the standard RHS Pro Elite LS7 Cylinder Heads.
These aluminum, CNC-machined heads feature a 307cc intake runner, 98cc exhaust runner and 69cc chamber volume. The intake valve is 2.250″ x 5/16″, while the exhaust valve is 1.615″ x 8mm. Designed for 454-502c.i. street engines, RHS Pro Elite LS7 Big Port Cylinder Heads are also ideal for smaller cubic inch, all-out race engines.
Features:
- Raised 307cc intake runners, 98cc exhaust runners
- 69cc Chamber volume
- 2.250″ x 5/16″ Intake valve
- 1.615″ x 8mm Exhaust valve
- Best for 454-502c.i. street engines, smaller cubic inch race engines
- LS7 Style valve train
- Accepts production and aftermarket intake manifolds