Proper manifold selection is critical and depends on the intended use when swapping turbos.
The new intake manifold needs to be used in conjunction with other mods to get the intended gains it was designed for. Just swapping in the new manifold wont give you any set of the pants improvement. You will see a definite improvement on the top end especially when you upgrade the the turbo.

3rd gens benifit much more from upgraded manifolds! Some folks have opinions that the larger number of #5 and #6 on 3rd gens could be related to less air flow! Some have even moved to 2nd gen manifolds but of course it take much more work!

I noticed quite a bit of spool-up difference between the stock manifold and the ATS I have on it now.

I just changed turbo and manifold last sat. I would def go ahead and do the manifold. I went from stock to an HTb2 62/12 and ATS manifold i think it spools quicker than the stock one

I have an ATS but I'm seriously considering the manifold from Hellmans. It looks sweet. Check it out.
http://www.hellmannperformance.com/1...20manifold.jpg
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