Cold Fussion wrote: If you had a problematic ICE, mgu-h and mgu-k, do you think you will be allowed to change the block, head, pistons, crank, mgu-h, mgu-k etc all under the pretext of reliability? There is quite obviously a limit to what can be changed and wholesale changes to the engine are not going to be allowed by the FIA.
Integration, and how MGU-h/MGU-k operate with the engine, combined with the recuperation and turbo efficiency is where the major performance gains are. But ICE upgrades occur and they don't even need tokens

Honda have already changed the turbo according to Auto motor und sport and TJ13...
http://thejudge13.com/2015/06/02/honda- ... rbo-in-f1/
And regarding the token free upgrade for a piston....
That said, the RA615 H problems have not been due to a lack of power, if anything the engine has been running capped to improve reliability. However, Honda got a free change of piston design (under safety and cost exemptions) for the Barcelona test, and so some of their reliability issues have now improved