In the UK ca18det bottom ends with 8v sohc ca20e style heads are making 200hp atw.
Even older head technology and with forged internals like Piggys ca and the right
manifolds, turbo and tune can make over 250atw no sweat.
There is a ca18det with 411 atw
http://autospeed.com/cms/article.html?&A=1249

Old bmw 2002 engine blocks where used in f1 turbo setups in the early 80s
only after the engines where seasoned with over 100,000klms then a
twin cam head similar in design to the ca18de where used with exotic
fuel for over 1500hp in sprint tune.

ca18det turbo engines give better fuel economy and performance compared
to more cylinders, capacity and price per unit.
They are also lighter than Sr and rotaries by a long margin.

The ultimate turbo Nissan 4 cylinder is still the FJ20ET nothing comes
close and nothing forever will from Nissan problem is weight.

Hi mate
My CA with a T28, intercooler, exhaust, chipped ecu, Bosch 040 pump and 15psi made 163rwkw so, with your current spec list, you should be able able to hit your power goal.
Matty

Cheap, Fast, Reliable... Pick 2.

start counting your back wallet son..

Id go less on horsepower and more on boost levels. Stock standard CA internals are reliable on 14psi... I know scotty from maddat motorsport has been trialing a 16psi with a high flowed T25 putting out near 170rwkw and thats a daily and hasnt had nething go wrong with it yet

i think they can handle a bit more than that, there's a guy on here that had 190rwkw pretty sure he had a stock block

the turbo is rated at 400hp as apposed to the t28bb rating at 350hp and it is a ball bearing turbo, tho im worried about the engine internals when under too much boost. ive herd the stock internals are good for 300 hp at the flywheel, is this correct?

i would do the injectors and get a good electronic boost controller then go get a retune, i would assume if the turbo is ballbearing it'd be good for 20psi if not find a good secondhand t28bb of an s15

thanks for the feedback so far guys. to answer some questions, im running r31 struts and brakes and im aiming at 160-180kw atw.
at this point gtr injectors with a bigger pump looks like a reasonably inexpensive upgrade, can you think of any others?

how much power you want?