I just want to make sure that if i get a RB catback for my s5 TII that i wont have to worry about overboosting and blowing my motor. As long as i have the stock dp, midpipe/cat i will be fine with a 100% stock car, right?

 

No this is not alright, its called boost creep. You need to port the wastegate.

Search and you will figure out how to do it.

 

He said catback, not turbo back. You will NOT boost creep with the stock downpipe/cat in there. I never did with a S4 tiny wastegate and just a catback system on my TII. The stock S5 wastegate is already 6 times larger than the S4.

 

thats what i thought, just wanted to be positive so i have no issues. Since i dont have the funds for the supporting mods that come with getting a turbo back exhaust im starting with a cat back..

 

The RB catback is practically stock, just better looking

 

really?

66 mm? why does it boost creep still?

 

Well fine then, actually read his thread and post useful information...see what I care.

 

You need to actually use math here:
S4: 13mm wastegate -> Area = Pi * r^2 = 42.25Pi
S5: 18.5mm + 25mm wastegates -> Area = 85.56Pi + 156.25Pi = 241.81Pi

241.81 / 42.25 = 5.72 times more area

You can't just add the diameters, that doesn't tell you anything.

As for boost creep, I can tell you that my car has ZERO boost creep with a open 2.5" exhaust system, and my S5 wastegates are ported to 23mm & 26mm. That is 25% more area than the stock S5 wastegates. The other important part is taking metal out of the cover plate so the wastegate door can open up farther.