I have an 86 GXL. I want to replace my exhaust system due to leaking and rusty components. I know that if I buy headers I need to get ones with the 6 port actuator pick up tube but I'm wonder if it would be okay to buy a downpipe and cat replacement pipe? would the ports still open or would they close up on me? Any help would be appreciated. Thanks!

 

With the stock catback, the actuators might work. Sometimes they do, sometimes they don't. Honestly though, the small gain from a downpipe and cat replacement isn't going to be much considering the massive restriction of the stock exhaust manifold. You'd be better off getting a set of headers, then feeding them into a high flow cat.

 

That's weird that they might or might not work. I'll just go with the RB Road Race headers and run two straight pipes from them back to the mufflers. If it's too loud like that then I guess I'll buy or make my own pre-silencer.

 

Any time you open up the exhaust, the amount of pressure in the split air pipe decreases. At a certain point, there will no longer be enough pressure to force the actuators open. That's why some headers and RB's presilencer have small diameter pick up tubes, and RB's even has a design with 2-3 bends to increase restriction.

 

That setup will be grossly loud. Don't think of not using a presilencer or two.

 

I figured it'd be really loud and I thought that the headers come with the pick up tube too? it says they do on the Racing Beat website.

 

The RB headers come with a pickup tube, but the backpressure from an aftermarket catback can still be too little to open the ports. If you want to make sure they always work, use the air pump to open them.

 

I knew there had to be something else to it. So what do I do if I'm getting rid of the cat.? Don't you remove the air pump then too? Just wondering, because I've been told I don't need the air pump and I've been told I do need it so I'm lost on that issue.

 

The RB exhaust system or whatever you go with should have everything you need for your 6 port to work. It gets rid of the cat. The S4's use exhaust back pressure to open the ports were as the S5's use the air pump. Somewhere on here there is a thread to change that around if you want. If you change out your entire exhaust with a new one from a decent place ie. RB, then the 6-ports should work fine and you could rid yourself of the air pump if you want.


Edward

 

I have an s4 so it uses the back pressure to open them. I'm not going to bother changing it around it'd sort of be a waste of time. I'm planning on getting an entire new exhaust system and I've always liked Racing Beats parts so I'm most likely going to go with them. After I get rid of the air pump I'm trying to put a dual belt pulley on the alternator too.