I have an E-manage on my car but I didnt tune it myself. When you first splice it in it will have absolutely no effect at all. You can tune the fuel straight away with the 5 screws on the front but its very rough.just 5 rpm points at + or - 20%.
Once you get the support tool you have a full 16 x 16 fuel map and if you get the optional ignition harness you also get a 16 x 16 ignition map.
Since its an intercept style computer if you stuff it up you can just put everything back to zero and run the standard computer maps but itd be more worthwhile to have it professionally tuned