Hi Victoir,
300bhp is certainly achievable on the 20VT and you'd probably just scrape in with the std T28 running around 1.4bar boost but charge temps are gonna be sky high as it will have to spin very quickly to maintain any sort of decent boost level at higher revs. You are gonna be pushing close to the design threshold with that compressor size so you need a good fully synthetic oil in there and I'd recommend changing it every 3-4000 miles otherwise the turbo is gonna suffer and will probably die prematurely.
You need to look very seriously at cooling the charge otherwise you are into diminishing returns (the more boost you run the hotter the charge gets and the more the air expands resulting in a net decrease in pressure so turbo has to spin even faster until... meltdown). The upgraded intercooler will help a bit but not as much as you might think. You almost certainly need to be into charge cooling as you suggest and I wouldn't leave it until spring.
ECU wise, obviously you are looking at a remap, I'm not familiar with the Millenium chip so I can't comment on that. I can say that the Novitech and the Unichip, both give good results. I'd be tempted to go for the Unichip and have it set up on a rolling road. I'd be surprised if you didn't run out of puff with std fuelling so you are probably looking at an uprated fuel pressure regulator and possibly fuel pump. You could go up an injector size as well but it can make the idle a bit more lumpy and I doubt it would be neccessary for 300bhp. Of course pre-programmed chips like the Novitech and Superchips have a set map so increasing fuel pressure or injector size is a no no with these chips. This is where the Unichip has a big advantage as it is programmed to suit your individual setup whatever that may be. Many people combine these with aftermarket boost controlers such as the Apexi which can give a lot of flexibility in controlling overboost etc but they are not essential.
The Supersprint exhaust is a good mod and will help the breathing to liberate a few extra ponies. Sounds great too without been boomy on the motorway and the fit is spot on.
The engine internals will probably be OK at around 300bhp but you certainly wouldn't want to go any more. I reckon you'll get away with the stock pistons as long as you keep the charge temps under control and the fuelling does not run lean (which is absolutely critical). Head gaskits on the 20VT are well rated and should take the power no probs. Similarly, bottom end is pretty darn tough and I'd say you get away with keeping this stock too.
You might find the clutch starts slipping a bit, if so then an uprated one is on the cards but I'd wait to see before comitting any cash.
As for the lowering, be careful as the ride can really suffer making the car crashy over the bumps. The suspension bushes also take a hammering so you might want to think about upgrading the material as well. In my oppinion for the cost Vs benefit of lowering the car I'd say it's not a good value mod. As said before, get the strut brace on and see what you think. Some people have fited an uprated anti-roll bar and reported good results but again it's a lot of labour for a modest improvement.
Good luck, and let us know how you get on
SpunkyM...
Fiat Coupe 20VT, Bailey DV, K&N panel, PBV @ 1.1bar.
