is there any performance gain from using aftermarket mufflers (dyanflo, racing beat, flowmaster, apexi, other?) on a stock Y pipe and and no cats? Right now I've got a pipe with no cats in it, and the factory Y pipe, debating whether to put the stock mufflers back on, or get new ones, and if I get new ones, which ones to get, and whether they are going to be direct bolt ons, or if I'm going to have to go custom and have flanges welded on them or something
thanks for any advice or info

 

racing beat mufflers will bolt on if i remember correctly. the rest would simply be a matter of having an exhaust shop weld them on for you.

 

Ive been wondering the same thing. and I want my car to spit fire!

how much performance gain can you get from removing/hollowing the cats?

 

I'd rather not spit fire if I can help it... as far as the performance gain in removing/hollwing cats, not sure on one with good cats, I had to because my cats were clogged, so in my case it made an amazing difference, LOL

 

i went from the stock 3 cat setup to a presilencer >high flow cat by bonez, with this and an intake it helped make a noticable difference, it sounds really deep without being raspy or loud, kinda a sleeper setup. (Tii y-pipe mufflers)

 

The RB mufflers will make pretty much no noticable difference if you're using everything else stock. But the gutted cat will make a difference... you will probably notice a slight loss of torque and a good increase in higher end. After the gutted cat (all stock) I noticed that it was just less sluggish... it's not an incredible increase, just nice.

--Gary

 

so if I replace my cats with a presilenser or test ppe itll change the sound AND give me better performance ?

 

what kind of intake did you use?

 

I used my stock Y pipe, I bought 2 mufflers from procarparts.com for 35 bucks each and they are steel mesh packed, so they should last a bout a week more than the cheap ebay ones . They made a whole new section so I could always take these ones off and put stock ones back on. Sounds great!! Very rotary like, il try to get a video up in the next month or so.

 

My cheap N1 mufflers hold out pretty well with 2.5 straighpipe to the stock Y then into the mufflers. Sounds awesome once the boost kicks in and you start movin. The best part is the mufflers are essentially "bolt-on" now with a little bit of cutting and welding to the old flange.

 

If you use a testpipe make sure that you find a way to keep your 6 ports open.

And if you want your car to spit flames, just go buy a Racing Beat header/presilencer. Its worth the $$.

 

the ports will open if you just put a plug in the rubber part of the Split air pipe that comes out of the Smog pump.

 

I just installed a RB catback on a buddy's NA. He has gutted cats and used the RB y-pipe. He hasn't really been able to get into it because the clutch hasn't broken in, but he told me he couldn't resist opening it up just once and was surprised by the power gain.
When I installed the RB system, I measured the y-pipe. There is NO DIFFERENCE in length, position or pipe diameter between a stock y-pipe and the RB unit. In fact, now that I've seen one in person I wouldn't bother with it. Just get the mufflers and connect them to the stock y-pipe.
As far as using the air pump for aux port activation, doesn't the S5 already do that? Not sure if using the air pump as a primary activator will open the ports at the right RPM without some kind of air solenoid. Has anyone here tried it?
BTW, gutted cats + RB mufflers + high-RPM upshift = flames

 

that would explain why my car was so slow on the way home with the exhaust removed (cats were plugged when I bought it) wouldnt run more than 5 minutes.... pulled the exhaust to drive it home, it ran and revved up but no power, gutted the cats, put them back on, hooked up the split air pipe, and pulls REALLY hard now