ash ecu first or cat back exhaust system?

what should i get first a ash ecu first or cat back exhaust system for my na 300zx?

first i would get the exhaust. ecu is a nice upgrade, but i always say the first things you do for a car is make it easier to breathe in and out.

Most people start out with I/H/E upgrade.

I'd do the exhaust first. Not sure what the "H" in I/H/E is......

H = Headers

i must be a little backwards. i did exhaust, intake, now im goin for headers, then ECU. probably just personal preference.

well now that i'm hanging around here, i might as well comment :) tee hee
personally, i like doing intake before exhaust.. a loud exhaust is cool, but having the car relatively quiet until you really get on it is sweet.. i suppose you can find exhausts that do that too, but meh, what can ya do:p
would downpipes on a TT be considered as the "H" in I/H/E? or is it really worth upgrading the downpipes until you get into the serious turbo upgrades and such?

Its probably not worth going to down pipes until you are forced to by a turbo upgrade (like the BB530s I'm putting in my car).

You can get the pre-cats off, but its not an easy task and putting them back on is harder. But it can be done and then you can gut them into fairly straight pipes, there is a FAQ on that at www.twinturbo.net.

This is worth a mild HP probably in the area of about 10 hp but improves throttle response a good deal I'm told, as the pre-cats are right on the back of the turbo, meaning its having to deal with a fair amount of back pressure right next to it.