ok i know this question is going to be vague. but a buddy of mine bought this msd box, or maybe it was a small coil . it was a small cylinder. but it wasnt one of those huge boxes. im real confused at what it was, bc im still looking at small things to do, and he said buying that msd part is a good buy. can anyone help, or kind of know what im talking about?

also, what else can i do to my truck...

heres what ive done..
-intake
-throttlebody spacer
-msdwires
-royal purple through the engine, transmission and rearend
-gibson headers
-magnaflow cats
-super 40 exhaust

heres what i want to do, but since im not keeping the truck for another couple of years, id rather not
-cam it
-change the gears.

what else can i do? im prolly gonna save up for mass air flow sensor. any suggestions?