In the course of corresponding with Mark Adams in the UK regarding some ECU issues, he recommended a number of mods, including Superflare trumpets (see other page) and new fuel injectors.

He kindly shared a source for me to buy a set of injectors. Turns out they were only available as reconditioned but that was fine - the major difference is the spray pattern. The stock injectors emit more of a stream of fuel whereas the newest ones emit a cloud of fuel which burns from the outside in, and much faster. This requires a 2 degree change in the base idle ignition timing (from 8 deg BTDC to 10 deg BTDC).

At the same time, I realized my fuel rail did not have a Schrader valve for measuring fuel pressure, something I consider worth having. So I replaced the fuel rail and the fuel pressure regulator at the same time as replacing the injectors.

All is running smoothly now, with idle at 10 deg BTDC and around 32 deg BTDC at 4000 rpm.

View of the new fuel rail with new fuel pressure regulator and 8 new (reconditioned) injectors.