You may care to have a read of this link if you are considering the Aldon Amethyst https://www.clubgti.com/forums/index.ph ... on.277614/Steve Payne wrote:This is the one that comes with a lot of good reviews, http://www.aldonamethyst.co.uk/" onclick="window.open(this.href);return false;
I have never actually fitted one but the principle is easy enough.
Another option is the OMEM200 Ignition Management System http://omextechnology.co.uk/ecu-200.html
Re the input type; Vacuum (MAP) or TPI .... The Omex website says "The Omex ECU can use an input of either throttle position or manifold absolute pressure (MAP). Most normally aspirated engines will use an input of throttle position as this gives excellent throttle response. Forced induction engines need to use MAP as there is no direct relationship between throttle angle and engine load due to the variable of boost pressure. However, forced induction still requires throttle position sensor (TPS) input for idle condition information. In some cases a MAP sensor can be used on a normally aspirated engine for load."
Hope this helps