Howards makes one.

I've used it with my roller cam in the 505 and have over 7,000 miles on it.

I had read bad reviews on the Comp one but they "disappeared" from Summit's website...

'63 Dodge 330
11.19 @ 121 mph
Pump gas, n/a, through the mufflers on street tires with 3.54's. 3,600 lbs.
10.01 @ 133mph with a 250 shot of nitrous an a splash of race gas. 1.36 60 ft. 3,700 lbs.