I'm no mechanic, so please excuse me if I say something stupid
What I know so far I've learned through searching... but still missing bits.

I bought this car a few weeks ago. From what I gather my 86' GXL (all stock performance wise excluding the RB exhaust) has: RB downpipe, stock main cat, RB y-pipe-thingy and dual RB mufflers. This thing is a bit too loud for my taste.

I'm thinking replacing the main cat with the RB Pre-silencer.

Will it be quieter?
Will the pre-silencer activate my 5\6th ports?
Will I see any extra fuel mileage?
Will the car stink of fuel without a cat?
Will I need any supporting mods to handle the extra HP from the RB exhaust?
Will I need anything else beside the presilencer (any extra tubing, etc) to do this?

I think I can answer half these questions myself... but I need security!
Thanks,
-Rick

P.S.: Does that look like a limited slip diff to you guys? Previous owner switched rear subframe but can't recall what type of donor RX7 it came from.

 

1. I doubt it will be quiter, maybe a bit louder, but def a different sound.
2. yes, assuming you have an s4
3. if the cat is clogged, yes
4. It will def. smell more.
5. no
6. You will need the downpipe, also. It is sold as a package on the site

Also, it doesn't have a LSD tag, but it could have been removed. You can test by putting the car in nuetral with the e-brake off and jacking up the rear. Turn one rear wheel and if the other turns the same way, its has an LSD. If it turns the other way, its an open diff or a worn cluth-type diff. The other wheel might also not move at all, in which case its a worn lsd.

 

Not to sound noobish but what is that tube going from your cat to the front of the car? My car has this too.

 

Split air pipe. Runs air to the cat to help it warm up.

 

And here I thought that was the way the 5\6th ports were activated

 

Not following you.

I thought I had the downpipe?

(Full RB exhaust)


This is the pre-silencer by itself:

 

If I were you I would dump the downpipe and go with the header and a presilencer.

It is the way the 5th/6th ports open, notice that it is on the presilencer too... with a presilencer you dont have cats so why would you need to warm up the non existant cats? lol

 

Right, forgot that the split air pipe also controls the 5th/6th ports on the S4.

 

Nevermind sorry.

 

if you want quiet, I think gettin rid of the downpipe and putting the stock one back in will make it quiet. I have almost the same set up, just without the downpipe, its not loud at all. But definatly wit a presilencer to replace the cat, its gonna make it louder.

 

I have the RB header to presilencer to stock Y pipe to some kind of custom mufflers and it isnt loud at all, and the header is alot louder than the stock manifold... are you sure you dont have a leak somewhere?

 

How come?

Yeah, that's what I thought until I got confused

 

The stock exhaust manifold is a huge restriction, ever seen one off a car? The RB header is far better.

 

But will it make it louder?

Power is not the goal - this thing is my DD. I want quietness

 

Yes it will make it louder, but I dont see how your current set up is loud at all, check for leaks.

 

I have a full rb setup with a cat in my s4 gxl. My car is loud when I gas it and start but it's quiet when I drive easy around 3k rpm.

 

I will consider ordering the headers\presilencer instead of just the presilencer. Money is not an issue here. That would be all I would need, no?

Would I need any supporting mods THEN?

 

You need the correct header, presilencer, header to engine gasket and 2 presilencer gaskets.

That will be all you need, besides alittle work to get it all in. Have fun with the manifold heat shield! That thing is a PITA to get off, there are two bolts on the bottom, then remove the 5th/6th port actuators and remove the two on top. Ratcheting wrenches help here.

 

Racing Beat is the only way to go!!! Louder, but def better!

 

Allright allright you guys have convinced me, headers and pre-silencer it is

I'll order new gaskets for everything to make sure.

 

good, if you don't like it give it to me and buy an electric car.

 

since your gettin headers, let me know if you wanna sell that downpipe

 

can you post sound clips when you're done? i wanna get the RB true dual system, but I wanna hear how the collected system sounds first.

 

1-Unless there is a hole in the cat, the pre-silencer would make the exhaust louder.
2-The GXLs come with LSD, and there should be a LSD tag/stamp on it. Otherwise spin one rear wheel and see if the other moves in the opposite direction.
3-Sell me the RB catback

 

Yes thats a LSD.


the cat actually lowers the sound of the exhaust.


Gil