turbo: blow thru vs. draw thru

What are the pluses and minuses of each system?
My brother put a pair of 280ZX turbos on a 340 in his Scamp. It was a draw-thru with a Holley 600 sitting on a sheet metal box and the turbos drawing thru a pair of long tubes with the turbos sitting ahead of the motor and the box sitting on the intake. It didn't look like it should work very well, but it did. It's all that's left since he wrapped it around a tree. Ran pretty good, but needed better gas. Should have gone with a bigger carb I think. You can see that the downpipes run out thru the top of the fenderwells. Stock exhaust manifolds were used. The stock wastegate system was used and stayed at 7PSI.Here's a very bad photo of it.