Bought my PIAA replacement bulbs at the Castle Coombe Rally day.
Rated 150/150W, but only draw 80/80W, hence no need to alter loom, etc.
They give a much whiter light and are a vast improvement that standard.
Cost about £70.00 the pair, which isn’t cheap.
The UK PIAA importers are based near Weston-Super-Mare, seemed nice chaps, try contacting them direct for best price.
Oh, yes, the box they came in is mainly in Japanese, but model/type appears to be
Platinum H.I.D. H4 80/80W and amp;gt; 150/150W H-89