I picked up my 2013 civic si sedan couple months ago. I love it! I want to pick up parts for it over the winter and install all of them in one weekend this spring when its nice. I have been doing a lot of research but would like some input on a couple things. I will start with the list I have compiled. Injen cai, OEM big bore tb, tbs?, catless downpipe, and full exhaust, and flashpro(tuned by vit)! FIRST QUESTION - Would I need a throttle body with the injen cai or would the tbs be enough for my mods? SECOND QUESTION - EXHAUST - Magnaflow 2.5" or greddy EVO3 2.75". I like the sound of the magna flow but im afraid it wont alow enough flow for performance. Im looking to keep it semi quiet with a deep mellow tone. I have about $2500 to put into this winter and would like the best performance for my money. I have been debating about the RBC intake manifold but I think im going to stay away from that for now.