Afraid not Neil but it is a well trodden path. Kirko and Steve P both did this before me. Stumo convinced me not to go down the aftermarket route, partly because of Dan's busted after market jobbie and partly because I've not ported my head. That is where the first bottleneck will be on my engine.
TBH, there is loads of metal arounf the ports of the OE manifold and its pretty easy just to take it out all round and smooth a few bottle necks.