Slowpoke what he didn't tell you was that he did a si swap in his dx(jus my) hatch now you probably can help him a little bit better
he's a cool dude but the only thing I can think of is that it's a wiring issue remember dx has the what dual injection and si has multi injection so what I have herd from other's that has done this swap before is that there are 2 to 3 wires that need to be changed
I think good luck tho