AdamSanta85

Tune. If you are concerned with warranty, APR Plus has that warranty tune...

manifold danger

I feel this right in my wallet. My 2015 STI required a tune if I looked at it wrong... and I traded it in with all those parts still attached (~$8k worth @ "stage 2"; Cobb turbo-back, cold air intake, 750cc injectors, fuel rail, AP + install/protune, and also JDM grill, chin spoiler, and LEDs). Somebody got some great value on that trade.

Also why I may never modify another car ever again.

VektorPerformance

What Mike said!

Sarawnty

I went with Soul HF cats first. I found the stock car way too muted for my liking. Then installed Vektor headers and then air filter. The equal length headers also changed the exhaust note. The sound quality was now perfect for me. I decided on the FVD tune for a number of reasons but mainly because I wanted a ‘mild’ tune for the street in order to preserve the power delivery of the base engine. I think the order you decide on for your mods is a personal choice but once you start, it’ll be difficult to stop. But if I could only do one mod, it would be the Soul cats.

Momentum Worx

If anyone is looking to improve exhaust tone, response, and add a little bit of power...

I have 991.2 Sport Headers in stock, and I have 991.2 Sport Cats for PSE cars arriving soon. Just let me know.