i'm willing to do it, but what would be better for speed? I'm stuck driving a slowass 82 diesel jetta

again what do YOU want ?
and what do YOU have right now ? most ES were v6
and how much you want to spend
let say you want an all motor car, (newbies take note all motor = no turbo no supercharger but Nos is ok, only a honda boy will say that he drive a all motor turbo civic )
to make power you will need a profesionnally ported head , a set of powerfull camshafts, a set of cam gears, a set of valve springs and an updated sets of rockers and lash adjustors
the same head is needed for either a 2.0 or a 2.4 the difference will only be choice of camshafts, like Crane #18 for a 2.0 and crane #22 for a 2.4
either the 2.0 or 2.4 you won't find a decent header on the market that makes power, because you need a true long tube header and it will need to be custom made
so head = same cost 2.0 or 2.4
bottom end forged pistons and forged rods cost the same 2.0 or 2.4
block: 2.4 cost a little more because 2.0 you could grab neon block by the dozen
pan: custom 2.4 or a decent pan like the moroso = same cost
fuel 2.0 would need #24 or #30 injectors 2.4 #30 or 36 or even #42
however the cost is pretty much the same
2.0 direct fit 2.4 you need some engine mount and creative work for power steering
exhaust work same cost
results : potentially 180-185 whp on a 2.0L for several thousands , 230-240 whp on a 2.4 for several thousands
now let say you want a commercial turbo kit
the cost of the kit is the same
engine wise the 2.0 would need forged internals
the 2.4 could use cheaper $wise but still very strong srt-4 internals
the head could even stay stock , same cost for the 2 engines
block : read above a second time
pan : read above a second time
the 2.4 will delivers tons of power 350 hp at 4500 rpm is easy to do
the 2.0 could delivers too but a 7000 or more rpm for the same hp
torque wise the 2.4 will be way ahead of the 2.0
if you only want an engine with a few bolt ons like 95% of the peoples out there don't even bother researching
Alain