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.
The EGR and EGRC-BPT can be disabled very easily to eliminate this hesitation and have no ill effects on the rest of the engine. In fact, these valves were left off the S14a and S15. Their removal should have no effect on your MoT emissions testing.
A number of people have completely removed the EGR circuit from the engine. This is more complex and doesn't achieve anything extra except tidy the engine bay a bit more.
First, locate the EGRC-BPT and EGR valves. They are fitted between the bulkhead and plenum. Remove the pipe arrowed on the EGRC-BPT (Figures 1 & 2).
Block the pipe with an appropriately sized bolt or screw and tuck the pipe out of the way.
Yes, that's it! No more irritating hesitation.