just upgraded :)

[castner]

ok so i just traded my black 2005 mz3 hatch for a white 2008 ms3. the speed has lots of mods already done to it and one of the big mods is that its catless. it has an ecu fooler or something that makes it pass inspection and no cel. would it be possible to do a larger diameter exhaust while still going catless and how hard would it be? i will post pics of the new car soon

 

[b e z]

No real point in changing the exhaust as it already produces optimal flow and you wont see much gains from it. Downpipe is the biggest gain which sounds like you already have that, any more tone wanted you could try a test pipe.

 

[MSMS3]

^ Well said.

The bottleneck is up in the stock downpipe and racepipe. That's where the restrictions are. With that taken care of, there is no need to spend big bucks on the CBE part, since it flows better than the maximum exhaust discharge rate of the stock K04 turbo. If you upgrade the turbo to something bigger than stock, only then does an aftermarket full 3 inch CBE to match the dp/rp begin to make sense.

Welcome, OP, to the world of high pressure direct injection turbocharged and intercooled Mazda. You will really like your car. There is lots of help to be found here. The search function is your friend, but it is sometimes difficult to use. If you can't find what you are looking for, consider using Google and put the word "mazdas247" (without the quotes) first in your search terms. Google should take you to this board and give you a good list of threads and posts on your search terms.