I'd say cc503 and 918 springs.

 

BTW: just because you read about some springs making a huge difference in HP doesn't make it so. Those mags are paid for by advertisers. I would be leary about a claim that behives made 40 more hp.JMHO

 

I have a cc306 ,355,11.6.1cr,2200tc, it needs a minimum of 3200 preferebly 4000 stall , BUT the car still screams you just have to keep the rpms up and frrom a roll, its a turd off the line but thats where my squeeze helps out. I have the comp pacaloy springs with a extremely high spring pressure to keep the valves from floating

 

you'll get valve float at high rpms with that particular spring kit