87RXGhey7

At the moment I have no cat but the stock mufflers. Is there a down side to adding free flow mufflers? I have heard something about the ports not opening, but dont quite understand(lack of backpressure). Please helpme out, thanks.

1987RX7guy

iTrader: (3)

S4 cars 86- 88 use exhaust back pressure from cats to open up the auxilary ports. As your car stands right now they are non-operational and you are not getting 100% power.

87RXGhey7

so wtf do I do besides wiring the ports open? Should I put a cat in and get free flow mufflers? What would be the best idea?

Rxmfn7

iTrader: (4)

Actually with a stock catback, even with no cat you probably have enough backpressure to open the ports. With my header, 1 HF cat and straight through mufflers, my ports still operate fine. Put some lithuim grease or something on the actuating rods, then go take the car for a spin, redline a few times. Now check the rods. If the grease is still there, they arent opening. If it has been smeared off and pushed up, then they are.

Icemark

with the stock mufflers, the aux ports are probably still working if there is the pressure line hooked up at where the cat goes (like the RB pre-silencer does).

Otherwise you would want to use the air-pump to activate them, you should search, there have been 100's of threads on this.

You don't want to just wire them open or you will loose low end power, making the already slow off the line N/A motor even slower off the line.

1987RX7guy

iTrader: (3)

Well you can use a pre-silencer from racing beat or a high flow cat from bonez. Those are made to operate the auxilary ports properly and still give you power.