Just chiming in on the Maxxecu front.
I am a dealer and tuner for Maxxecu and I know I am biased in saying so but it is hands down my favorite to work with. But this comes from being a professional calibration specialist for 20 years working with all your typical brands and systems on everything from air cooled street motorcycles to all out max effort championship race vehicles.
Here is the last 911 I was involved with. I provided the Maxxecu and tech support to the shop installing it and wiring it. Provided a base map and then calibrated using my Dyno Dynamics Dynotech chassis dyno and then road tuning after. The engine combination and calibration made for a terrifically smooth power delivery and excellent street manners.
Engine is a mild 3.4 liter with a Will Pyle assembled top end using KR75 cams, Apgar spec CP pistons, stock ports, PMO throttle bodies, SSI small tube headers with modified Dansk muffler (great low end torque but sacrificing top end power) and a Maxxecu Street ECU.
Video shows a dyno graph with calculated flywheel HP and torque with math developed in house by Dyno Dynamics (manufacturers of engine dynos as well).
This is my personal 3.0 liter, I went with RHD individual throttle bodies go with a Maxxecu Race ECU. This one will be a high rev'ing, big port, high output setup to push my targa around.
