Yup, they're designed and fabricated by the same company that make exhausts for these guys:
http://www.radicalsportscars.com/uk/ So the quality and integrity of manufacture & materials far exceeds any other manifold for sale for early Polos, granted the price also exceeds them. Both have a purpose, the Raceland items are suitable for the lower end of the market, and designed for non-G40 applications. Ours are designed with performance in mind, for the heavily tuned G40s running in excess of 170bhp.
Several years ago we re-designed No. 1 runner to give increased clearance around the charger mount, allowing G60 and Eatons a better chance of fitting. There's several subtle design features (runner diameter, hole>flange welding etc) too.
My only change would be a reliable split feature for the manifold, stock uses 4 bolts and two flanges, which in time seize, and are prone to leaking. PSD tried a sleeve joint, which don't seal 100% (not ideal to have leaks pre-lambda) and also are nigh on impossible to split after 18 months on a car.
That said, you can remove a charger, access the oil filter/alternator etc with the manifold in place, so there's not many instances when you need to remove it on its own.
Lastly... they look the tits.