The main difference is that Rado still make use the original turbo-back sections of pipe, which are a bit squashed. I assume they're made that way to make fitting easier at the factory.
There's a thread
HERE on mine with the pictures so you can see what I mean by squashed.
Both systems have pros and cons, and both considerably improve the exhaust note. The Weistec system is
LOUD but opens the thing up to allow maximum flow from the turbos with no restrictions. As you'll notice from the pictures though, there's no provision for a cat to be fitted but lambda sockets are in place. This to me meant a lot of "check engine light" until I had the lambdas mapped out. The Rado system has options of either full, sport or no cats.
Fitting wise, the Rado is a straight bolt on job, achievable in an hour or two, and can be reverted back to standard in the same time, whereas the Weistec system is a nightmare. No room to manoeuvre around the engine bay, limited access and mine took two guys the best part of 8 hours to fit. The eventual solution was to remove the engine mountings and move the engine across for each side, but still not a 10 minute job.
I can't speak for the Rado system performance wise, though do know a few guys who have fitted them (including Peter above) and nobody seems disappointed. I went for the Weistec system as it was new, and I suppose I was the guinea pig really, though I'm glad I did as it still makes me smile.
The main difference I found when I had mine fitted was the low end performance, with maximum torque now coming in at c2,000rpm and going all the way up the rev range. Under normal circumstances this makes for much easier driving as the car's not shifting down as much for overtaking etc., just picks it's feet up and goes effortlessly and with a nice deep burble.
Whichever system you go for get the car mapped to suit it, ideally on a dyno at the time, and then just sit back and enjoy.
ETA: Not sure of figures on mine at the moment but the bum dyno says "sufficient".
