Redoing Kitchen Sink Plumbing

First I would like to thank anyone who replies in advance. I am redoing the cabinets in my kitchen. The previous were about 30 years old and it was time. Upon taking the cabinets out and taking a closer look I found that the drain was going to be an issue with the new cabinets since their was a cavity to hide the drain in the previous corner cabinet. I really don't want to cut up my new cabinets to much. It is currently a 2 inch drain with a 2 inch vent. To me the way the drain goes into the 4 inch looks wrong and it really doesn't have enough slope. I also live in ontario canada if that comes into play with codes etc. My question is should I change the drain to come from below and then hook up the new double since and dishwasher so I don't have to cut up the cabinets and cut thru any studs?