Rick,
I am TDS-70 1/2 over there.
I might suggest ATR for stainless downpipe, etc. I have those pieces and they are N-I-C-E! There's enough areas that these cars can improve before even getting to the turbo and intercooler. Cracked stock headers can rob power, restrictive stock exhaust robs power. I've been eyeing up the ATR stainless headers, these non-intercooled cars are much more responsive to header upgrades than the IC'd cars.
I just threw out the 33 as a starting point. There's plenty of owners here running even bigger. Contacting one of the vendors could get your the right one depending on performance goals.
Starting from bone-stock, as you say, my feeling is these steps:
fuel pump and hotwire kit
adjustable wastegate, to allow higer boost level.
(hand-in-hand with this is a scan tool or at least a knock gauge, 'cuz once the boost is turned up, bad things like blown headgaskets, can happen)
An open element air filter, like a K&N.
Those alone should net some noticeable improvement. From there one could start looking at:
headers, crossover, up-pipe and down-pipe. Lots of cars run a dump-pipe so it can be uncorked, but I have no real intent of racing my car hard core, and I don't care too much for the sound of these cars with open exhaust personally. I intend on running mine thru the exhaust system.
New ECM chip. The '84-'85 ECm can be swapped for a version from the '86-'87 cars, which would be a good idea, due to teh lower cost, and greater chip availability.
turbo, which will also require fuel injectors that flow more. Exact size will vary depending on ultimate turbo selection.
Intercooler kit.
Notice that none of those steps are numbered. Because ya can't always just do step 4 and not look at 5, for example. The WHOLE package is very important with these cars. One could write multiple books on figuring all this out. And I'm not one that is able to do that, I'm just sharing what i've read over the years. I am hopefull I will get around to applying some of thsi to my T-Type one of these years. Sadly, the very slow progress on the old Camaro is keeping me from even starting on my Regal.
I guess without knowing for sure what your customer wants the car to run really, knowing how many of those steps are going to be necessary is tough. My gut feeling is, the smaller stuff should be done before throwing new turbo and intercooler at it. 'Cuz it's all going to be needed by the time the car does get intercooled anyway. If ya got someone with BIG pockets, do it ALL. What I'm trying to express to ya is, there's a lot that can and should be upgraded, even before the parts you originally mention. It feels to me, and I could easily be way off not being right there, but your customer maybe doesn't understand everything about the car, if they are wanting to throw those parts on a bone-stock setup. You would be in for a world of headaches to try and get it running right without all of the small steps being included too.
Clear as mud, right?!?!?!
