1) from my reading here and elsewhere the Mountung MR230 tune is good for 225 whp. So you can make things rather interesting with just a tune.
2) In the time I've been here I've come to conclude that the stock engine just isn't capable of holding up with a larger turbo. Yeah, I've seen all the posts about how the cast pistons in these engine can withstand 300 hp but I've also seen posts about 300 hp setups blowing holes in the pistons. Granted I haven't seen any posts about 250 whp setups blowing up pistons but I cannot remember ever reading about someone building a 250 whp bigger turbo engine, it seems everyone wants to do 280-300 hp.
3) At 300 hp you really want to retain the stock downpipe. Not only will it save you money but it's also been designed so that there is a standing vaccum wave at the outlet of the turbo, which means you'll make more power with the stock downpipe.
4) An old (as in ancient) hot rodders trick for a "hidden" power adder is a Larger Radiator. Because an engine running Hot won't make as much power as an engine running at the ideal operating temperature. Many of those Deuce Coupes were running radiators out of a semi tractor. Point is, toss the stock radiator and install a Mountune 3 pass and you'll find full power is 100% available even on a steaming hot August day with temps pushing over 100.
5) Power isn't cheap and never has been. Unfortunately with the complexity of today's engines the cost to replace an engine is very expensive. The days of getting a 100 dollar runner from the junkyard and doing a shade tree rebuild are long gone. So when working on a power plan you need to anticipate how you stage everything. Throw a bit turbo at an engine too quickly just increase the odds for a blown engine. For me the staging goes as follows.
Stage 1 is Cooling, because Cooling is critical for both the health of the engine and consistant power output. So the first things you should do are the radiator and the intercooler. Adding a Water/Methanol system at this point is worth considering. Granted these systems aren't cheap but a good meth system can allow the use of a much more aggressive Tune and it can also act to keep your intake valves clean.
Stage 2 is Breathing. At this point you'll want to address the intake and exhaust systems and take a rational approach. For instance, with only 1.6 litres (98 CUI) you really won't need a 3 inch exhaust until you pass the 400 hp point. So save yourself a bit of weight, and reduce the volume a bit by installing a 2 1/2 inch exhaust. On the intake there is a wide variety of options available so my only recommendation here is to chose a system that has excellent filtration and easy servicing of the filter. I'd also recommend getting a system that doesn't trigger "codes".
Stage 3 is the engine block. Specifically Forged Pistons and premium connecting rods. I also recommend some type of cylinder support system because I just do NOT like an open deck block in an engine running 300 hp or more. If I ever decide to go for 300 hp plus my plan is to get a Mountune MRX Longblock or perhaps the complete engine. I'll also note that after seeing posts about Mountune's engine builder lacking some attention to detail I would plan on checking the torque of every rod cap, main bearing cap, and ever other critical fastener.
Stage 4 is where the Fun starts. You've built a good solid foundation so you can throw just about anything you want at the engine. If you are only going for 300 hp you can get there with just a turbo kit. If going over 300 hp plan on a larger turbo instead of a hybrid and you'll also need supplemental fuel and a Water/Meth kit.
Here you go again spreading misinformation. The engine is perfectly reliable with hybrids and larger turbo’s running up to and around 300 whp. Most the people blowing up their engines are pushing them at upper boost levels and running around 350+whp . We are talking 30+lbs plus boost levels. Which most tuners will not tune for unless you are running aux fuel aka secondary injection system with E30 or more tune.
A larger radiator is important for our cars because the stock radiator is wimpy it will make no difference in power.
What will make a difference in being able to sustain power and boost is a bigger intercooler that will not heatsoak.
Water meth systems are not needed on our cars for cooling unless again your are going for insane numbers and even then its not an absolute requierment.
Your stages are also made up. lol There are stages except for classifying tunes and even that is partially made up hotrod internet BS. lol
Oh and I have friends running 300 to just over 300 whp on stock blocks reliably no problems.
One does not need to spend the money on a Mountune shortblock unless they are planning on hitting 400+ whp on a regular basis.
Plus engines are not expensive you can pick them up all day long in the yards for around $700-900. That is cheap.
$100 an engine is like 25 years ago. lol and would be stupid cheap now.
Oh and the fun starts even with a Hybrid in the 260whp range. I have driven those cars. I would bet you have not as usual you speak from no experience on our cars.