Unless you have a new high pressure fuel pump or fuel pump internals down pipe should be close to one of the last bolt on's you do. The down pipe on the speed3 is super restrictive and once you put a free flowing down pipe the fuel system can't keep up and you get lean spots.....lean spots = boom. It would be a good thing to get ether a cobb accessport or a hypertec also for tuning before a down pipe. I prefer cobb because you can edit any tune and they are always updating.
Now that is said......
The corksport dp is great they have a devorced wastegate so you don't get boost spikes
cobb would be another good option though more expensive.
Stick with name brand no ebay crap
Also you will want to ether go with the ptp pcv pill (30 bucks)or the cobb pcv fix so your turbo doesn't start smoking
As for CEL'S you can ether get a race cat in the dp or a O2 bungle extender (pulls the o2 sensor up put of the exhaust a bit to eliminate the cel problem and its way cheaper). You can also turn off this cel with the cobb ap