I started a similar project, I wired up 4 car automotive bulbs (i bought 8) to an attiny and using shift registers i make them blink in sequence, I used TIP31's though and it works nicely providing you put 12-14v through (the voltage drop makes it visibly dimmer), i got them blinking real pretty, I tried two IRF's n mosfets as well, they worked almost identically in brigtness, even fading in and out like an LED, I think i used a 1k bleed resistor though but i'm sure it worked identically, i've got to build the damn thing anyway it's a christmas display.