As far as Lotus is concerned there is only the OEM stock and the HTU ( High Torque Upgrade). They do not provide a whole lot of documentation on either one. There are chips you can buy (not from Lotus) that have been modified to remove limiters on boost or cat deletes (Red Race chips) but you have to have sockets installed so you can switch back and forth between the stock chip and the Race chip so you can pass inspections. Using the race chip removes the "safety" limits that Lotus put in so they could offer a warranty on the car. IMHO the small gains in performance are not worth the risk of damaging the motor. A properly running Lotus V-8 is already more car than most ordinary drivers can handle. Adding more power will just get you into trouble quicker and damage a lot of expensive parts. A better way to spend your money would be on a driving course like Skip Barber and make sure your car is in the best stock condition you can get it to. For example, if your tires are over 7 years old they should be replaced. BTW, your ECU should already have the HTU. You can verify it by checking the labels on the case.