midpipe
 

I'm gonna install a midpipe soon. I don't have a boost controller, but I have the apexi fuel controller. Will it be ok for the engine? It's a '94 RX7

is this "fuel controller" a new ecu? Are you talking about the PFC? Then Yes I would think it's ok if that what your talking about.

No, it's the apexi super AFC.

Those are good for tuning when removing fuel, but not for increasing.

I would still recommend some sort of boost controller when adding your midpipe. What other mods do you have on the car? It's possible that adding the midpipe could cause you to experience "boost creep". In that case, a boost controller won't help much since the wastegate will be doing all that it can.

Does it make any diferent on an automatic car ? My car is an automatic.

Not really. A/F ratios and Boost creep are the same whether you have an automatic or a manual. The difference just comes into play when you change out the stock ECU.

IMO, unless you are in a hurry for a rebuild, you should look into getting a hi-flo cat instead. That will add some power while still keeping enough restriction in the exhaust to keep problems like boost creep away.

Even then, you should think about a boost controller.