[A4] KO3 or KO4 turbo for my A4 (B6)

[Arthur Marks]

I think the strange random sound coming from my A4 is the turbo going bad 
(inconsistent grumbling at low acceleration).

I don't want to get into too many modifications. Would upsizing the turbo 
with just a chip tuning be any better or do you have to start changing 
exhaust, injectors,... to get any benefit from it? I would be doing the work 
myself so suggestions on where to send the chip would help too.

Thanks,

--Art
 A4, (B6) 100k miles