When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I used these guys for a 4" aluminum mandrel bend I just bought for my truck, they're way cheaper than everybody else. http://www.globaltecheng.com/elbows.htm
Flexible tubing/ducting, I'm not sure, that same site has some I think...also most dryer vent hose is 4".
For most of you ducting 4" single wall vent pipe works well.
Much better than dryer vent because of the smooth inner surface.
Single wall vent pipe also has adjustable ells.
Most hardware stores have it.
Also a pair of tin snips can cut it to length.
And lastly it is not overly expensive.
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Slideshow: The VelociRaptor Expedition gains a lift, upgraded suspension, Brembo brakes, and trail-ready equipment while retaining the stock 440-horsepower EcoBoost V6.
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.