can i do a DIGITAL 400 Watt Grow Light with cool tube set up

i have homebox xs 2x2x4 have a all in one 250 watt hps but i want to do a DIGITAL 400 Watt Grow Light with cool tube set up .will the tent get to hot .is this tent to small for a 400 watt. i can get the light for $199+shipping $29 1 NEW 400 Watt Digital Ballast This Digital Ballast has built in "smart chip" and AUTOMATICALLY adjusts to Metal Halide or High Pressure Sodium bulbs.1 COOLTUBE 19 LONG 6 WIDE
1 Set of retractable light hangers
1 High Pressure Sodium Bulb
1 Metal Halide Bulb FREE!!!! should i buy this ok price yes or no

htg, i'd go for it i plan on upgrading to a 1000 watt digital myself.