What power gains should i expect?

[Dino]

You'll end up paying for tuning twice if you go for tuning first, and you'll not get the most out of the first tune as the OEM manifold will be restricting it too much. Doesn't really make sense to do it in that order.

+1 to that

[K4MR411]

Any particular reason for the 2WS conversion?

Im not a fan of the 4WS and ive always been driving about with it disconnected, but i hear thats dangerous so im just going to take it out. Also to save weight and so i can have the rear arch sitting a tad over the tyre

You'll end up paying for tuning twice if you go for tuning first, and you'll not get the most out of the first tune as the OEM manifold will be restricting it too much. Doesn't really make sense to do it in that order.

+1 to that

Yeah that is true. Well, you just won me over

Now, another problem. Last time i was talking to Solid-Fab about a custom manifold, he mentioned that he would require the standard manifold to work from. I live in N.Ireland and that would mean taking the manifold off and sending it to him and then him sending both, custom and standard manifolds back. Thats going to cost me extra money and a lot of hassle.
I would get a manifold made over here, but everyone i have asked have said they would only do exhausts and everyone just buys DC Sports one which are sh*t

[Dino]

Put a post up in wanted section for a mugen/fujitsubo/RSR manifold.
Great off-the-shelf items.