My 84 GS needs a new exhaust. I am going to swap in a T2 motor over the winter, but would like to be able to drive it around for the remainder of the summer/early fall.

If I bought this exhaust from Racing Beat:

http://www.racingbeat.com/FRmazda1.htm

could I later swap out the header for a downpipe split to a Y then connected to this exhaust?

 

Anybody???

 

I am assuming you are reffering to the street port system with dual pipes. Your link just opens the main page at RB.
This could be done, but I would suggest just getting the stock port header, and running a custom 2.5-3 pipe from there. Everything from the header back, just go ahead and run as if the turbo motor was already in there. That way, when you get it installed, it will be exactly what you want, and prolly not cost as much. Far easier to sell the single outlet header used, vs the dual pipe. Most who would buy a used (even slightly used) header, do not have the money for a complete system.
Just my $.02 worth.

 

Ahh. Good idea.

 

I'll accept the used header, as a commission, LOL.
Seriously, I have 2.25 stainless pipe under mine, starting just after the first bend under the manifold. I think whoever put it under there, had intended to eventually get a header. As do I, just wish someone offered a stainless header. Guess I will hafta build my own SS header...........

 

Will the pre-silencer from the Racing Beat FC turbo-back fit under an FB? I loved that exhaust, and am thinking that I could go 3" all the way back. What muffler to use though?

 

I would think it fits. Considering there were originally 3 cats under there.........
You may have to have the pipe custom made though, as the routing could be far different.
As for muffler, any decent sounding/free flowing single from an FC should be great. Even the "ricer fart cannons" have a decent tone on a rotary, but can be a little louder than most like. A presilencer would eliminate the sound issue, though. I have one of these on my car, also installed by the PO, and other than just a little louder than I want (at times), it sounds good, in my opinion.

 

you can retain all parts of the exhaust except for when you have to swap out the header you may need to takeit to someone who does exhaust work