To do the job once and properly your looking around 5-7K. IMO RS would be wasted on forged internals. 28/30 71 is the really good choice.

I know that you have said that you want 350 bhp - have you considered around 330bhp? You could keep the standard internals, and go for a GT28RS running lowish boost and achieve that without too much trouble without headwork on a standard engine running good compression as long as you have the relevant supporting mods. 300bhp would be a breeze on a 20VT.....would not cost a lot to get there, and the car would be very driveable on the road.

Standard injectors will also flow that without / without 3.8 bar fuel pressure....they will be maxed out, and it is preferable to go bigger, but then costs do start to mount up.

It would be far cheaper to go this route, and as you mention that a 2871 would be too laggy for you I doubt that you really need to think about a fully balanced, flowed, and forged engine....if I was to go down that route I'd go for a GT30 and learn to live with the lag.

I would look for a modded coupe to buy in the first place that is running strong compression - even if it ends up needing a re-build it would likely end up cheaper than starting with a standard car in good condition.

but as long as the car is VERY well known, I don't think you have anything to fear

Lukes car has everything you want. Maybe change the turbo to one that suits you, get it remapped and you have everything done (including handling) for less than £6k including the car.

Jules - buy Luke's car!

It will be massively cheaper than building your own AND you'll be on the road straight away.

Its possible to get a coupe to 330 - 350 for not much more than a couple of grand, but it'll be right on its limits and it won't handle well. I guess you'd probably want it to handle and stop better than standard as well, so there's another grand to spend if you're doing it yourself.

OK - its satisfying to build the car yourself, but as long as the car is VERY well known, I don't think you have anything to fear

Really? Can you give a break down of where the £5-£7k would be spent please? Remember I've already said that the 28/3071 route is not really the choice I'd opt for unless there was obvious reasons to change my mind. I am happy to go with the GT28RS as from my previous experience these were more responsive than the slightly laggier bigger brothers. So possibly no reason to go forged internals?

Jules.

You said reliable 350BHP which means a FULL rebuild with forged internals.

I did said a proper build so:
Pistons & Rods £1300
Oil pump £350
Block Boring £120
Head rebuild no porting £200
Balancing £150
Turbocharger £700-1000
Gaskets sets and shells plus other bits from Fiat £500
Clutch £600 paddle £450 organic
Injectors £140
Downpipe £250
Exhaust £300
FMIC £350
SIP £80
Airfilterr £50
Oils £100
Pagid Blues £140
Heat Wrap £40
Build Labour £500-800 (Depending)
Mapping £400

So that’s about 6K already. Scary when you add things up

Perhaps you should define 'reliable'.

Works for 10k miles?
Works for 50k miles?
Works if I poodle along on the commute and only boot it occasionally?
Works if I take it to the track and wring its neck?

Can't help feeling there might be different answers.

I have recently upgraded from a GT28R to a GT28RS but with the bigger .86 housing. There is a bit more lag (maybe 200-300rpm but the top end pull is 10x better. Might be a consideration as i should be over 350bhp now

With the list I have given you above adding the fuel pump gives you the ability to run upto 450BHP depending on turbo choice. I think it would be a waste to go through all that and stick on an RS with “lag” as a justification I know I’ve been there, in fact I’ve had four turbos on mine and driven many others too. IMO the RS is for those without forged internals and pushing the limit. If you’re not going down the rebuild/forged route then make sure you plan for it later down the line because it will go pop. The 71's are NOT laggy in fact I’ll bet I can out pull any r or rs