Help figuring out which heads to buy

[Badasssapper67]

Hey all, I want to buy a set of heads as a project for later down the road. I want to get more familiar with the dohc engine for one, and I like putting my personal touch on my cars.
I'd like to clean them up (not port them) put in larger valves, better valve guide seals, better springs, keepers and locks.
This would be a one step at a time, do alot of research then a little work, kind of deal.
What Im wondering is, how available are the 9 thread heads? I'd like to avoid spitting out a plug but it sounds like the 9thrd heads are hard to come by.
Also Im guessing it would be smart to start out with 03/04 heads instead of the 99/01?
Would FR500's require any special intakes or gaskets?
I dont want to waste money, but this is a side project to help me get aquainted with our engines.

 

[na svt]

FR500s aren't worth the expense as the 03/04s will make the same power. 4 thread heads are fine; all 4v heads prior to mid 04 had 4 threads and there were few issues with them. The FR500s use the same gaskets as the other C heads.

Use springs that work with stock retainers as that will save you some money. Also, .5mm oversize valves are as big as you can go without changing the valve seats.

 

[Badasssapper67]

Heads

FR500s aren't worth the expense as the 03/04s will make the same power. 4 thread heads are fine; all 4v heads prior to mid 04 had 4 threads and there were few issues with them. The FR500s use the same gaskets as the other C heads.

Use springs that work with stock retainers as that will save you some money. Also, .5mm oversize valves are as big as you can go without changing the valve seats.

Thanks. Sounds like the best thing to do is get my hands on a set of 03/04. In your opinion is half a mm bigger valve worth the effort and cost?

 

[na svt]

.5 oversize valves add a little power. Opening up the valve seats and using the stock valves is much more cost effective.