I have a mk7 gti that has a type s catback borla exhaust i want it to be louder and i was thinking of the cts catted dowpipe but im not sure if i need to tune my car after and if i do what tune do i need for just those two parts everything else is stock
I also have the Borla Type S Catback on my MK 7.5. I can say with the stock downpipe its plenty loud for most tastes (in a good way, the tone is deep and rich enough without inducing drone). I know when I go with a DP/EQT in the future, I'll need a solution that at the very least takes care of the drone. GTI Jake here makes DPs and a mid-pipe Vibrant resonator kit for the Borla Catback, which (as they've put it) places the volume/tone inbetween their Less-Aggressive CBE and Aggressive CBE offerings. So that is one option you have, and in my opinion with my experience with Jake's products before, is the best option. Either way, if you go with a DP you'll need a resonator to handle the drone.
That said, do yourself the favor and get an intercooler first. When you're ready for the downpipe, set aside the money for an EQT tune as well via your Cobb AP.