Renewing the inlet and exhaust valves, along with these RETAINERS when overhauling the cylinder head is desirable.
New ones will ensure good a seal, as long as the seat is reground. So with reliable valve actuation engine performance will improve when compared to the old worn items.
You will require new VALVE SPRINGS to help ensure the valves don't 'float' at higher revs!
Have you ordered ALL the valve springs, gaskets and seals you may require! Don't forget the gasket sealant, try 08C70K0234M - for a more professional result!