I do have the full Kooks dual with green cats setup. I wouldn't buy it again. It immediately started rusting - and I'm in Denver, not the rust belt. I put it on a couple years ago and it looks like garbage now - not that I care about the looks too much, but the mega rusted ass bolts are super fun. Parts have fallen apart, some covered under warranty (resonators fell apart internally), some not (mufflers). Maybe they would have been, but it's impossible to get a hold of Kooks. I had to replace the mufflers entirely cause they just tore apart from general use, not from impacts or anything. The whole assembly has split in half at the rusty clamps probably six times, but I got REALLY good at putting it back together. I had it down to about 5 minutes, carrying the proper tools in the bed. After the last time I went in and had it welded together, no more clamps. I have to constantly tighten the flange connections at the front of the setup when I hear them leaking. In short, Kooks sucks, and you can't talk to them. Sorry you already have their product. I'll never buy their junk again. At least the cats have held up.
I'm not sure about needing a tune prior to the Whipple. I'd recommend asking JDM, but I want to guess it would be beneficial to get one, but I don't know if you NEED one.