waste gate placement

[efficient]

i was wondering were is the best place to weld on a external wastegate.

i have a cx racing turbo manifold 1st gen with no wastage provision. is it best on the downpipe or on the manifold itself?
also what size wastegate is recommended?
I'm looking to reach close to 300 whp.

found this

http://www.treadstoneperformance.com/blog/the-dangers-of-improper-wastegate-sizing/

[gotaloveRWD]

On the manifold itself you want to position it so gasses will flow easily into it
If you put it to far away or angle it wrong the wastegate won't open at the psi you set
I think, I'm no expert just read a book

Edit: just checked out the link you posted the four pictures explain visually what I was trying to say

[Northern]

My Dan Pinder manifold has one added on like this. I believe the CX racing mani's are knockoffs of this design, so it should work.