I had a s14a for 3 years and bought it bog standard and in the end had it dynoed at 411 bhp.
Very underrated in stock form but easily modified and i did all the work on it myself. I actually ran the car on a stock bottom end for 2 year and did 25k miles at 370 bhp.
I then built bottom end but ended up selling car for a good sum.
All u need is a bigger/better turbo and i can say the hks gtss is one of the best for street use along with hks cams, z32 afm, ecu, metal headgasket. arp bolts. 555 nismo injectors and fmic for a serious road car.
I ran 12.8 sec drag times with street tyres and full interior.
Gearbox is good for nearly 500 bhp in manual form as long as u have a decent clutch.