www.ipdusa.com sells a cat-back exhaust. It is expensive and
a local muffler shop might be a better way to go. I've never
heard of an after-market intake manifold being available (intake
systems are designed with super-computers these days). The entire
intake system is designed to flow enough air for the turbo model
so it is not a weak area in the car (and it has a cold air intake
from the factory so no need for after-market kits). 99's are also
hard to chip so a chip for a non-turbo might be difficult to find.

Overall, there are not really that many performance accessories
available since they have to compete with the Turbo models. It
is actually much cheaper to sell a non-turbo and buy a turbo-model
then hot rod a non-turbo. The turbo engine is not just a turbo
bolted on. It includes forged pistons, lower compression ratio
engine, thicker cylinder walls (or smaller piston bore, depending
on how you look at it) intercooler, sodium filled valves, lots of
check valves, different water pump impeller, heavy duty radiator,
etc.

I've seen people answer this question before and suggest spending
the money on a high performance driving school. They say it is a
blast and the skills learned will keep the car moving faster then the
after-market parts would. (Sounds like fun to me.)