The major difference from going with Resonated and Non-Resonated is the Drone inside the car and the rasp outside the car. Resonators reduce drone inside the car and the rasp outside. The do slightly decrease the volume overall. The lack of rasp with the resonators causes people to call the resonated systems deeper but its really just removing the rasp. I have the 18" Resonated system with the standard mufflers. I have not yet received my Headers and have the stock cats.
No matter what setup you go with FI you are going to make a great choice! As for Tony's customer service it has been impeccable. He always returns calls as soon as he can. If you call him and tell him what you are looking for he will explain all the options and what the differences are. He spent over 30 minutes on the phone with me when I ordered my system back in July.
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Injen Long Tubes|FI TDX CBE#374|B&M Short Throw Shifter|Nismo Polished Aluminum Knob|Stillen 19 Row Oil Cooler|20% Tint with Front Windshield Strip|Michelin Pilot Super Sport
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