Difficulty is you don't quite know exactly what your getting then, I've a fortune in my car due to massive issues when i converted to cossie management and messing about with second hand cvh's, I then got rid of the cossie stuff and bought new megasquirt, had that mapped for cvh turbo, got sick of the cvh and went full zetec, but now its mapped perfect and was all worth it and I know the car pretty much inside out.