You know absolutely nothing about Alex's or Alex's friends knowledge and experience so kindly keep your snide comments to yourself

Having never fitted greys before and as they do not have the conventional euro clip fitting and we are dealing with fuel in a hot engine bay under 3-4 bar pressure do you not think it wise to ensure that they are fitted absolutely correctly???

I am a qualified mechanic and just because I've not fitted greys before does not mean I shouldn't attempt it, it simply means I should ensure I know exactly how they fit before fitting them.

It's not just a case of sticking in a chip, injectors, winding up the boost and hoping for the best.
Alex knows that, who are you to assume he doesn't??