Just bought a hx40 on impulse....

[driftmonkey]

I sold a turbo I had for my r5 gt turbo so had some funds in my paypal and have just bought a holset hx40 but now thinking this will be to big for my m20 2.5. Anyone else running a holset? Going to run megasquirt and not sure what manifold, have a choice of two, eBay one and a mosselman

[chinese]

HX40 will work just fine, I don't know if yours has an internal wastegate, if so the wastegate is useless.
I'm not running a Holset myself but there are enough guys that do, maybe you will have a little bit more lag than a HX35 but it will be much more efficient at higher boost(10+ psi)

About the manifold:
Don't know if the mosselman has a port for the external wastegate, if it doesn't I would go for the ebay manifold because it's probably cheaper than mosselman.
There's actually an ebay manifold now that has the external wastegate port.

[Gunni]

the mosselman is not designed for high flow. You´ll have alot of backpressure.

[driftmonkey]

ive just seen the new design manifold on the bay, tempting, i'm starting off with the mosselman and a small turbo for 6psi , then later on change for the holset and a different manifold