Mazda Talk Forums

Hi all

Having a little difficulty installing my new RS3 muffler on my '98 NB (I am in Australia). Apologies if I've missed something obvious, I am new to modifying my car myself, but after reading the reviews and install instructions, it sounded pretty easy.

So I've removed the OEM muffler and am at the point where I'm fitting the new one. I'm having a couple of issues:

1) The stock midpipe has some bolts on it which don't seem to come off, I guess the ones supplied are only for the RS midpipe? That would be fine but they seem to be about 1mm too narrow to fit the new flange on. I've tried to WD40 them but not sure what to do there. Should I file the holes on the RS3 slightly to fit? Should I try and bend the bolts out? More WD40 and patience?

2) The holes on the gasket provided seem to be for the RS midpipe rather than the stock midpipe. Should I drill new holes into it? The OEM midpipe flange is looking a bit rusty and sad, I feel like the gasket would give a better fit.

Advice much appreciated.

Hmm, for the NB here that gasket fits with no mods, same with muffler. Our motors for NB were always 1.8 liter here, but perhaps yours there has smaller 1.6 motor? If 1.6, indeed might need to slot the holes for gasket and flange more.

Brian

Definitely 1.8 litre NB. Gasket definitely has the holes in different places though. Guess I will need to do some modding.

So I have had to drill out both gasket and flange to fit, and when I finally did get it to fit, it leaks anyway. I have
tried the drilled gasket only, the drilled gasket plus the stock gasket, and now I've waited 24 hours after using high-temp gasket sealer. All of these have resulted in similar significant exhaust leaks.

Not sure how this has happened. Is there a difference between the NB8A and NB8B exhaust system? I'm surprised that I seem to be the first person that's had this issue.

Help much appreciated.

Indeed never had to drill flange or gasket on USA cars, and we have sold thousands here. We can supply our dealer down there with some extra gaskets on their next shipment, which is soon, and they can hand you a few extra if that helps. My guess is that some markets got smaller pipe in the systems, particularly for markets that might also have used the 1.6 liter motor later than USA (that motor ended here with 93 production). Now that you have stock muffler off the car, be interested to know measurements of pipe diameter and distance between flange bolt holes, center to center (perhaps we can slot the holes more in our flange in next batch to better fit what was done with version sold in that country).

I think I've (partly) solved the mystery. I didn't mention that it's an auto trans because I assumed it wouldn't make a difference. But after digging around in your shop (the AU distributor only seems to stock the RS muffler) I note that with the Racing Beat there are differences in the exhaust between the auto and manual.

I have confirmed that my NB is definitely a 1.8, only 1.8s were sold here, according to Redbook. Anyway, I measured the dimensions between the bolt holes, they seem to be about 8.0cm, which differs a fair bit from the 8.8 listed here. So likely the reason is that I'm the first NB auto owner to buy the RS3 in Australia I guess.

I also measured the interior dimensions in of the midpipe, seems to be a shade under 4cm, so ~1.5 inches.

So it seems that in my enthusiasm I have bent the OEM bolts outwards, so they no longer accept the OEM gasket I bought. I'm thinking that my preferred solution is now, rather than drilling the exhaust again, bending the bolts, and hoping for the best, to get a replacement mid-pipe that we can be sure will be compatible with the new exhaust (and stock NB8A header).

My question is, will the 'RoadsterSport Midpipe with Catalytic Converter and Resonator, Federal Model' fit the OEM header, or am I just going to run into the same issue again?

Thanks

No idea and no way for us to answer the question given that NB exhaust for automatic is not the same here as there.

Thus, i cannot recommend the midpipe for owners of automatic in Australia.