A question on exhaust if I may

I am following the Buschur upgrade sequence and am a little confused. I hope you guys can help me out. Step 2 is this:

2. Cat-back Exhaust System
AWD with 12 or 13 sec goal:

Buschur Racing 2.5" Pressbent Aluminized piping with Stainless Muffler and 4" Polished Tip - 1G or 2G (AWD Only)

All Turbo FWD or AWD with sub-12 sec goal:

Buschur Racing 3" Mandrel Bent Stainless piping and Muffler with 4" Polished Tip - All Turbo FWD and AWD Models

Now I have read a few posts and people say that it is best to do a turbo back. If i understand correctly, that is a down pipe all the way back. I also read there is a 2.5 and 3*. My question is this: Will I have to make any modifications to fit a 2.5 or 3" down pipe to my turbo or does the down pipe fit connect fine from the flange then goes to 2.5 or 3' from there?
I also read that if I use a 3" that I could get boost creep I have to look boost creep up again but it doesn't sound good. What would be the best muffler to use? I have listened to HKS systems and they sound nice. I don't want the loud sound I hear the kids using around here. I also wanna keep my dual tips if that is possible.
Buschur says do the down pipe at stage 2 of the upgrade.

Any advice would be appreciated guys. I was told I would feel an increase in power a little bit. Hey... I have to start somewhere:naughty:

Thanks in advance guys

thank you for doing a bit of research first. when it comes to exhaust components you forgot one thing. The turbo connects to the 02 housing, the 02 housing connects to the downpipe. The 02 housing can accept 2.5 or 3 inch, it doesn't matter, they both fit. I suggest the 3" exhaust, and just port the turbo and manifold, there are threads on how to do this already. Also when people mention a turbo back exhaust, they usually mean an 02 housing as well, you can get 02 housing's that flow better than stock, or just port yours.

Can I add the components and port later?

You could just not worry about the 02, and just make the exhaust come right off the turbo, and drille and tap a hole for the 02 sensor. Right? you could make it 3" all the way off the turbo. Stock turbo as in the A/t Turbo or the M/t turbo, if you have the 14B turbo, i think the 3" all the way would be perfect for it. I don't know though.