Do they make 86 Nissan z31 cone K&N air filters, or do I gota buy an airfilter for lets say, 240SX? Basically you just have to go buy a rubber hose that will fit on the intake and the air filter then buy clamps?
You can use a few different size filters. The one in the pic above is just one of the choices. Actually a filter that big is not necessary but it works just as well. I used k&n part number RE-0930. You can also use RE-0810 which is basicly the same filter but longer. If you want to see what these look like go to k&n's website and do a search for these part numbers. You can also use their guide to check that the RE-0930, the smaller filter, is more than enough filter for this size engine. Also you can just attach the filter to the resonator like in the above pic or you can get a 3 inch diamter pipe that is more or less as long as the resonator and put that in place of the resonator. The resonator is just there to keep the intake quiet when reving. Without it you'll notice a "growl" when reving which some people like. There is no kit that you can buy for our cars so just make your own, not to mention it's cheaper anyway. Most kits are 100+ dollars but making your own will be about 50-60. good luck
I bought a Reactive Airfilter today for 30$ installed it and I noticed a big difference, I want to find somewhere to Dyno my car both with my stock intake and the reactive intake to see the difference.
no reason to, its already been done. The ractive filter with the resonator removed yields a 3HP gain over the stock box/filter with a 2 TQ gain. Turbos yielded a 8HP gain and 4TQ gain. neither of these increases are "feelable".