Thread: What size should i go ? (300Tdi Exhaust)

If you go 3" you will have to run a muffler and resonator.
Don't listen to anyone that says "it's a turbo, it doesn't need a muffler" as IMO they have no idea what they are talking about.

Without a muffler at all, the noise is horrific, you will be heard at least 5km away (and that is no joke) and the resonance right at 100km/h in 5th (80km/h 4th) will make the ears bleed as the cab becomes the resonator.
Fit a good straight through muffler and resonator and be happy with the better spool up and higher rev range of the engine.
I have a good resonator and a small straight through muffler and it's still too loud and tiring on a trip.

A 2.5" system would probably work damned near as well (stock is 2,3/8"-60mm) with less noise.
2.75" would probably be ideal, but the tube is exxy and mufflers not as easy to source.

I've got a 2½" with straight through muffler only, mandrel bent on a 300tdi Discovery. I've driven it with the flex joint completely destroyed and open to the world and it was rather quiet so when I had the exhaust done I had no muffler to start with cos I figured it'd still be quiet but... I'll agree with Rick, it really does turn the cabin into one big resonator - the guy who made the system up for me explained that the longer the pipe, the louder and more resonant the whole thing becomes, the turbo really does act as a muffler, but it all comes undone by the time there is 4m of pipe afterwards!

In all honesty if you're trying to make it sound good, at the end of the day its a 4cyl diesel, they're never going to really be audio-porn.

In your case with twin exhaust stacks 2½ inch really should be sufficient, it made a noticeable difference to mine in terms of better/faster spool up and I could get an extra 750rpm or so from the engine (was about 3800 max, now a little over 4500) just going up that little bit in size and mandrel bent.

Seano

I have a 2.5" system on mine, and a straight through "muffler" in the middle - it is loud but no problem on the freeway with resonance but it's just a bit too loud when going up hills for my taste. I will be trying to get a better muffler to make it a bit quieter. I've heard a 3" straight through system and it is very loud - hurt your ears loud. A compromise would be 3" downpipe to a decent straight through muffler, then 2.5" out the back or up behind the cab.

I was thinking of leaving the down pipe on and removing the middle muffler and the last muffler and running 3" mandrel bent with a resonator and straight through muffler in place... So getting back to the question, 3" would be plenty if you are going from the turbo back...if you are leaving the front pipe on, then I would just go for the 2.5" system

The General Consensus on AULRO is 2.5 " inch Exhaust with a Straight Thru Muffler in the Centre and resonator in the back. That's what I got on my 300tdi Disco.

Originally Posted by Disco_owner

The General Consensus on AULRO is 2.5 " inch Exhaust with a Straight Thru Muffler in the Centre and resonator in the back. That's I got on my 300tdi Disco.

Sweet!

On my 300Tdi 110 i removed the centre muffler and replaced it with a hotdog and removed the resonator at the end of the exhaust , The exhaust pipe was the only original part of the exhaust left
The noise was not that bad as others have said they sound crap what ever you do to the exhaust