gsl rb exhaust to gsl-se rb exhaust,
 

Hi there guys.. i have a beautiful '84 rx7 se and i recently picked up a bargain, a full streeport racing beat exhaust for only $250!
The only problem is that it was made for a carburetor'd four port 13b, not a fuel injected 6port 13b like my car is.
So i have weighed up all the options that i know of and i will have to weld a fitting to the rb header for the o2 sensor and also have to fabricate a backpressure pipe onto somewhere around one of the two presilencers.
That brings me to my first question being, does any one have any suggestions as to where i should locate this backpressure pipe?
I looked on racing beat's website and on their streetport exhaust for the gls se their backpressure pipe comes out of the prescilencer approximately 1/4 of the length toward the header and goes back toward the muffler about 6 or-so inches before doung a u-turn back to the direction of the header. I assume the pipe is long in order to cool the hot exhaust gas before reaching the rubber hose, check valve, 6 port actuators and the engine itself.

My other question is somewhat related to my first question.
Would i expect the 6port actuators to operate differently because the pressure in the exhaust which they operate will be different to the pressure generated by a stock exhaust system?

Question 3 is, my rb exhaust is a few years old and has slightly different exhaust tips than the ones pictured on racing beats web site. The rb website shows rounded tips but mine are almost sharp enough to cut myself on. Does anyone know if they are the only differences rb has made to their street port exhaust systems over the years?
Thanks alot in advance to anyone that can send me their help and opinions.
From Jozey.