If you want the fastest, get GIAC X chip. If you want something that's
faster than stock, but performance isn't No. 1, get APR. The boost
level tappers a lot more on APR so less power. It's also easier on the
turbos. Get the APR Bi-Pipe and be done with it. Even the Samco TBB
can tear. For DVs, get 710Ns. All aftermarket ones are not worth the
price since they do the samething and some even require maint. You can
get a pair for free when you order the Bi-Pipe from ECStuning.com.
Last I check the offer was still going on. Good luck with the S4, I
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