Litz Wire

I am accumulating 'junk' for my next tesla coil.

I have a few questions about my proposed secondary.

1) I am planning to use a piece of ?sewer? pipe.  It is about 1 foot in
diameter and about 5 feet long.  
	1) L/d ratio is about right - no?
	2) The pipe is made of "plastic."  I know that's not very 
	   specific - which is why I am looking for help.  There is no
	   printing which says: ABS or PVC or anything else.
	   All I can say is it's green and "plastic."
	   Anyone recognize what I'm talking about.
	   Is the material know to be good/bad?
	   (If nothing else - I can at least see what disolves it -
	    that should give me some clue.)

2)  A while back, I got a whole lot of Litz wire. (Surplus so almost free.)
Has anyone experimented with using Litz wire for the secondary?  I tried it
in one of my smaller coils  (3 inch diam, 12 inch long) and compared it to
a coil of exactly the same form factor - but wound with straight magnet wire.
There was no perceptable difference.
So, before I start winding a few thousand feet of this onto the big coil, I'd
like to know whether I'm doing a) a good thing b) a stupid thing c) it doesn't
really matter thing!
I figure, if nothing else, the  'cloth' sheathing will do a great job of
absorbing the polyurathane that I normal coat my coils with.