Congratulations on the new ride. Like already stated only you can decide when you need to make the change. Only had my Nismo since February so I'm still in the honeymoon phase. Good luck I have enjoyed many of your posts.
I ordered and installed my hood dampers from Kanjo and I was impressed with the product and the installation process. I highly recommend this upgrade and vendor. I found the directions were helpful and also watched the videos to ensure a smooth install. Absolutely love this upgrade. 
I have installed the Borla S-Type and must say I love the additional sound and quality of product. I have taken the car out for three long drive under various conditions and have no drone at any speed in inside the vehicle. wonderful sound when you start up and at any time you hit the...
Jimmy, appreciate your response and hope this will not be my experience. Had this system on my Corvette for many years and was pleased. Will post pictures and sound clips once received and installed.