I bought a set of stealth heads and put them on my race car back in 2008/09. I took them out of the box and bolted them on. My engine is a mild race engine compared to most, was 10:1 with a .533 mopar cam. I later put a .557 solid cam in and changed the valve locks from 7 degree to the 10 degree ones. I ran the heads for 5 years before having someone do some hand porting on them (didn't make a different in my combo). I did end up putting new valve springs on then as well since I had 2 or 3 broken inner springs I shifted the engine at 6000, would go thru the traps at 6500. Most will tell you to have things checked over, but for a street car, I wouldn't have a problem just bolting them right on, but that's just me. If you have to buy new valves and springs for your steel heads, I'd think your going to have just as much in them as the alum heads.