i've been doing much the same but with HREW and the same bender, and without heat it will kink, and with heat, it will bubble a little bit.
I'm gona fill the tube with sand to keep it from collapsing, and heat if necessary.
What size tubing are you using? I'm using 1 3/4" .120 wall. <img src="/forums/images/graemlins/cheers.gif" alt="" />

89 4Runner
3" BL, M/T locks, 33"bfg mt, bilstein, Kayline, tubebumper, toyotafiberglass panels
TBI: Elocker,3.4 w/ORS,b+b,S2Sstg2cams,arias pistons,P+P intake,TRDs/c,URDpullies+7th,downey headers,MAPECU2,WEGO WB, SupraMAF,walboro255,stg4clutch, EPaOo2 sim