The bigger exhaust housing crates less backpressure. It will also increase spool up time (how much is somewhat arguable) and may lower peak boost a little.
That being said, the wicked wheel is supposedly slightly less efficient, which is why it tends to help get rid of surge.
If you are at sea level, it might now be a bad idea to get the bigger exhaust housing, and it may help with the surge. A wicked wheel may or may not get rid of it too. If you are trying to get rid of surge, the the ported compressor housing is probably the best way to do it, but not the cheapest. My advice is to keep up the research and get to understand how it all works and then make a decision based on your use and needs.