There are some here, but, they aren't precisely cheap. About a third of the way down the page.

 

here you go sir! 10.95 per spring!

 

Mancini racing is a buck cheaper per spring, and you'll need the retainers and locks as those MP springs aren't beehived like the stockers. the stock retainers won't fit the MP springs.

you need 16 springs, retainers, and 32 keepers.

 

Mine were 20 cents cheaper per spring.

 

I'll add that I did not have to cut the seats to use those springs. Now, I am using EQ heads, but they are supposed to be stock replacements, so it SHOULD be the same scenario.

 

One more thing to add, the stock valves are steel, not stainless steel, just regular steel. I do not know how well the valves will hold up top a higher seat pressure, or how well the induction hardened seats will hold up to a stronger closing force. It's possible the valve could break up top at the retainer groove.

In all honesty, I'd just go with a set of EQ heads from a place like Clearwater and you'll get a better built and flowing head, stainless valves, and new springs to boot

 

If I had the money to get new heads I would......I called up hughes and talked to one of the techs and they have springs that they state will fit with no problems and are good to 600 lift, for under $6 a spring looking at $92 for just the springs, and then $62 for the retainers.

So far thats way Im leaning anybody see a problem with that

 

Springs are balance. You only want enough seat pressure to get the valve closed and enough open pressure to keep it to the cam at the rpm you want to hit.

The problem is high lift and rpm require higher open pressures,and thus the seat pressure ultimately has to rise due to the limited availability of spring height.

I don't think you have to worry about the stock valves until you surpass about 50% over stock seat pressure. Even at that you could go to titanium retainers and locks to reduce weight and reduce impact.