I don't remember the name of the place that I got the 3" rubber elbows from, but a google search, or some of the truck (big 18-wheelers) supply places have them. The only tough one to find is the 3" to 3.5" reducer at the MAF sensor. The intake elbow (oval one right at the throttle body), is this one, available from Summit et al:
http://store.summitracing.com/partdetail.asp?Ntt=intake+elbow&N=0&part=VOR%2D4GH112%2D050&autoview=sku&Ntk=KeywordSearch
The tubing is just mandrel 3" aluminized exhaust tubing with a big @ss K&N filter.....
BTW: JTR also has the rubber intake elbows: https://shell7.tdl.com/~jags/Pages/Parts_AirClean_Ducting.html