My engine harness is fried and I have thought about just getting the Haltech Platinum Sport 1000, but will this harness fit the stock ECU or is it just for use with the Haltech? Kind of newb q but anyway.
If not, how does the Haltech basemap compare with stock S5 TII w/ maybe a downpipe and an aftermarket intake and how is it to tune?

 

The Haltech harness does not fit the stock ECU. It's only for use with the aftermarket ECU. The is a full replacement harness available from Haltech for the FC which simplifies the installation of the system. We also produce a similar harness, built to customer spec. Either of those options allow you to remove the stock emissions harness all together and all critical engine functions are carried out by the Haltech ECU and it's harness.

Any base map should be thought of more as a startup map. It will get the engine started, but from their each engine combination needs to have it's own calibration performed for optimum performance and reliability. The Haltech, and most aftermarket systems, allow you to properly calibrate for any modification you want to perform; from mild to exotic.

The ECU Manager software is certainly one of the best on the market right now. However, "how is it to tune?" is a hard question to answer. The answer is based on your own knowledge and skil of, not only this particular system, but basic engine related functions and how the changes you can make in the calibration will effect an outcome.

If you have any specific questions feel free to drop me a PM.