Marko, what size are your valves?
Standard inlets are 33.8mm i believe? This means the valves will start to be restrictive at about 6000rpm.
If the inlets are 37 mm, the max unrestricted flow is at about 7200rpm.
For £1600 i'd want oversize Titanium valves and a gold plated receipt! Maybe it would be best to find your friendly local machine shop...
Personally i hate the term 'polish' as it's the last thing you want to do. Deburr is the way to go. Polish should refer to finishes of 32 microinch or finer. The finish you're looking for in an inlet port is about 63 microinch. Basically what you'd get if you use 240 grade wheels. If it's too smooth the fuel can drop out of the mixture and condense on the port walls. Bad news.
Is this another example of dodgy terminology? Probably...
I do it all the time myself
My hoover is a Dyson. No it's a bloody vacuum cleaner uurrgghhh... Shoot me now.
On the subject, i thought the TS ports were fairly good and just needed radiusing around the valve throat and deburring the valve guide/ port interface. If you're re-cutting large valve seats you'd need to do this anyway...
Peter, you're exactly right. The mods have a cumulative effect that is entirely different to the individual effect of any one mod. That's why you need to plan where you want to end up. The annoying thing is that since your exhaust is only matched to one tuned state, you're going to be running a compromise unless you do all your mods at once. A good exhaust is the key. Not an 'off the shelf' manifold from one company and a cat-back system from another. How can they hope to match?? Let alone match the non-standard cam you might have fitted?
Anyway, for example, if you want a tractable 190 bhp then you should be able to achieve that on standard cams and oversize single TB. So:- (just for an example)
Fit CDA - 155hp
Fit oversize TB - 155hp
Fit Exhaust - 158hp
Fit big valve head - 160hp
None work really well while there is restriction from the other areas
Fit all four - 190hp
Ok, ok, you'd need adjustable cam wheels to play with the exact cam timing, and an ECU remap, but you get my drift?
Think, a Focus ST170 can make 190bhp with only the addition of free flow cat, matched cat-back system and CDA, and that's using a single (standard) 66mm throttle body. OK, it comes with a big valve head and decent exhaust manifold, but it also has a nice wide powerband and is fully tractable on the road.
The moment you start using longer duration cams you really need to switch to isolated runner TB's to prevent charge robbing due to the flow momentum effect of the valve longer overlap, so big cost... Unless of course you just bodge it and loose bottom end & top end power and suffer rougher idling. Think back to carbie days. There's very good reason the Alfa Nord lump was fitted with twin 40's... So another cost vs performance & tractability decision...
Again, the advantage of fitting the larger valves is you're not using silly high revving cams to get the power, so it's there at the lower revs and useable in real road situations. Depends how serious you are, and what you want to do. It is, however, entirely possible..