Please check out my reply to your thread on BOV. I respectfully suggest that you take some time to read the stickies and learn about how our cars respond to mods. It seems you are more interested in sound (BOV and cat back) than with performance. That's o.k., if that is what you want.
But neither that BOV noisemaker nor an expensive (or used CBE) will make you more power. You need a good aftermarket intake (see other thread response), and you need to know that the stock CBE's on our cars actually flow better than the maximum output of the stock turbocharger. Yes, they are that good. A CBE will only change the sound and not increase power unless and until you add enough other mods to get you over 300 whp, which really means a bigger turbocharger for all practical purposes.
Many guys here who want to change sound, and know that they are doing it just for a change in sound, play with deleting resonators instead. Read the threads on that before spending your hard-earned money on fancy tubing and tips that do not make more power at your mod level.
There are serious restrictions on the exhaust side, but they are forward of the CBE. The stock downpipe and midpipe both have low-flow catalytic converters. And the downpipe is poorly shaped to maximize emission control. To uncork the exhaust, the trick is to go with an aftermarket 3" downpipe and racepipe, either catted or catless, connected to the stock CBE via a reducer at the connection point. You need larger tubing up close to the turbo where the exhaust gasses are still very hot, but by the time they get to the CBE they have cooled down enough to flow freely through the stock exhaust.
But, be forewarned, you really need to upgrade the high pressure fuel pump internals to take that step, and really should then go with a tune. Take me very seriously about the fuel pump upgrade. Failing to upgrade the fuel pump internals when messing with increased flow on the exhaust side or increasing boost level can be fatal to your engine.
I'm sorry for droning on, but I see that as a new MS3 owner you are falling into the trap of modding this car as you might on some other platform, or based on advice from people who are not familiar with what makes our cars work better. Our cars have very different ways of responding to mods. As you hang around and read the threads here, you'll pick up what works and what does not, what makes power and what is ricer bling.
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