If you need to do some budget plumbing consider GI water pipes.
Or steel pipes. You get them in 1,1.5,2 inch etc sizes.

For the bends just cut the pipe at an angle with a hacksaw. Rotate and weld.
This creates a sharp bend. And our little HM FLow bench was showing presure drop when compared to a proper mandrel bend setup a rich kid had on his Honda.

Get some GB weld / Goodsons Epoxy. Mix up a ball and use it take the sharpness out of the bends. End results you can get even these to flow as good as the best mandrel bent pipes.

 

Yeah its adds about another 80 lbs. to your car. Its a bad Idea no matter which way you look at it.

 

its cheap so i guess it serves a purpose

 

I used it at 4 bends.
In total 180 grms weight was added.
All you need is a hacksaw and a gas welder. Some water GI pipes. For free from the junk yard.