Combination caliper/handbrake solutions are not as good as dedicated caliper/disc and independent parking brake solutions. The S14 and S15 both have rear combination brakes. A relatively straightforward conversion is to fit the rear brake setup from the Z32 300ZX.
Fitting a boost gauge is a relatively simple task when you know where and what to look for. It is more fiddly than difficult. I have provided a number of photos to assist in the fitting of a gauge into a A-Pillar GReddy mounting pod.
The A'PEXi AVC-R (Actuator Valve Controller Type-R) is probably THE best electronic boost controller current available. It allows control over exactly how much boost to apply AND where to apply it throughout all gears and revs.
If you are running more than 12psi of boost, you should really upgrade your fuel pump. The standard fuel pump will start struggling to deliver enough fuel above this and that means your could start running lean at higher revs. Running lean means Det and bye-bye engine. Even if you simply need to replace the fuel pump, replace it with an uprated pump, as it will undoubtably be cheaper than the Nissan replacement.
Standard Recirculation Valve Removal
The Exhaust Gas Recirculation (EGR) Valve and EGR Control Valve (EGRC-BPT) were fitted on S14s only to reduce exhaust emissions and not much else. They do, however, have the nasty side effect of causing a noticeable power hesitation at 2300-2500 rpm.