It's about time now to really start thinking about doing something about the engine in the car now and the way I see it I've got 3 options each with their own pros/cons.
 
1. Keep the big port, add cams, MegaSquirt PNP and possibly ITBs:
Pros:
Relatively "cheap" and the engine I've got works well (so far)
No fabrication
"Legal"
Cons:
Leaves me without a spare engine
It's an old engine with lots of km
 
2. Buy and fix up a small port, add cams and possibly ITBs:
Pros:
Slightly newer engine with more power stock
Good opportunity to learn some engine work which I'm yet to tackle on my own
I can take my time to fix up the engine and put it in when I'm happy with it
Cons:
Possibly a bit costly
After market engine management seems a little bit trickier, or expensive
 
3. 20v Silvertop
Pros:
Newer engine
Sufficient power in stock form
Relatively cheap
Cons:
Could cause trouble if defected
Rather disappointing performance according to several people
 
Basically what I'm after is a noticeable power gain without spending a fortune. Not after making crazy power.
 
Any opinions?

I am in a similar position but I think I am going to go with your first option. That way I can do it in stages as the budget allows. Maybe megasquirt 1st (so I can ditch the afm) then the cams. It is probably more expensive than going a standard silvertop or blacktop but I like that you don't have to chop up the harness (a bit if you go ITBs) and a spare head or engine is quite cheap. I picked up a decent second hand engine for $500 a few weeks back after exploding the original at the track day in January so it is not a major issue if an old big port lets go. Although it would be nice to put together a properly built one,
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Im with carmikey, option 1 or 2. I would personally lean towards option 1. But 20valves are really not that amazing, unless you have the money to modify them further and tune them.

Thanks guys, pretty settled on option 1 now. Advantage being the availability of MS PNP (even though it'll cost me more than an entire small port engine). But it should pay off once I start doing further mods versus running the factory ecu on a small port.
 
So loosely my plan looks like this, please let me know if you've got any opinions as I'm rather new to this:
 
Stage 1:
Proper oil/water temp gauge + oil cooler
 
Stage 2:
Mega Squirt
 
Stage 3:
Cams (272/272?) + TRD 0.8mm head gasket
Adjustable cam gears
 
Stage 4:
ITBs
 
And somewhere I'll try to fit clutch/flywheel and possibly a c56 tranny.
 
So much for budget build... 

I am thinking I will go for a high lift cam with a little less duration. Normally you would need to go with a shim under conversion but the cam buckets in the link below seem to be a neater, simpler and cheaper solution.

http://club4ag.com/faq_an...s/Lifter%20Tuning.html

Also a good review of various cam options if you haven't seen it already.

http://club4ag.com/faq_an...E%20camshaft_story.htm

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I was looking at the specs of similar engines to the 4age and many have 10-11mm lift in standard trim. Even with durations similar to stock 4age. Apart from the shim arrangement I don't know why the 4age has such comparatively short lift. Bigger lift and shorter duration should be a nice combination of power and drivability.

There are a range of factors that affect ramp angle and asymmetric profiles can run shallower open than close. Time at maximum lift also affects ramp angle. Granted 11mm, 230 degree is probably not going to fly but Toda do a 10.3mm 264 degree that I would like to have a shot at. Be interesting to compare that with a shorter lift longer duration
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