How Quiet Can You Make An Mi16?

[eob 7]

I'm not really into exhaust noise and my Mi16 is actually quite loud. I used a modded Peugeot Partner CAT pipe, cut, twisted and then rewelded, retaining the GTi's centre and rear boxes.

 

As it is the car is very 'boomy'. Not massively so but I'd like it to be quieter..

 

pS. Seems to shift a lot of air volume, even at idle there's an incredible pulse of air out the exhaust. The 8v was like a mouse trying to give CPR to an earthworm, the Mi16 is like an industrial heatgun, I'm going to use it to shrink heatshrink from now on

[sideways danny 0]

GTI boxes are not great at silencing IMO, the center box is hollow so gives quite a distinctive noise. You'd easily improve on it with better baffled boxes

[eob 7]

That's the thing. Unusually, all the noise seems to come from the rear box.

 

In an ideal world, I'd like to junk the center silencer and just fit a decent rear expansion box...

[GLPoomobile 958]

I managed to make mine super duper quiet about 8 months ago

[Tom Fenton 1,542]

Do you have a genuine or pattern rear box? I've fitted pattern rear boxes before and found them horrendously noisy, whereas the standard stuff is quiet.

 

If you were really keen on getting it quiet, and didn't mind the spare living in the boot, you would probably be able to fit the standard 405 rear box sideways across the car. It is quite a lot bigger than the 205 item which is probably why the 405 is quiet with a standard exhaust on it.

[B1ack_Mi16 67]

I've made some exhausts from scratch for the mi16 engine a few times..

 

And my experience is that you should fit the biggest possible centre and rear silencer that you can.

Even with straight through free flow silencers my 2.3 race engine is completely quiet from the exhaust, and no boomy resonance either.

 

I've built some before also with some smaller silencers on a normal 1.9 mi16 engine, and it was bloody boomy so I think silencer volume is critical, get as big ones as possible

[paulvancraen 0]

Agreed, the volume is very important. But don't take freeflow dampers (the ones you can look straight through), those are really loud!

 

Also I wouldn't discard the center silencer, it makes alot of difference...

[eob 7]

Standard GTi Bosal backbox. Fitting the 405 one would be a lot of hassle but possible worthless. The main problem is it's a drone, actually seems to get quieter with revs

[Gentrix 2 1 Cars]

I managed to make mine super duper quiet about 8 months ago

 

 

 

I guess it doesn't run at all, otherwise your statement is a bit pointless, isn't it?

[trialster 0]

managed to fit a 309 gti back box on my 205. doesn't seem much quieter tbh..

[GLPoomobile 958]

I guess it doesn't run at all, otherwise your statement is a bit pointless, isn't it?

 

Oh it runs, I just got pissed off with it (again) and abondoned it up the road for the last 8 months With a DES Stainless Grp N system on it it's not quite so quiet when it's running

 

Either way, my comments here are in indeed utterly pointless

[KRISKARRERA 2 1 Cars]

My 405 is loud and boomy. Standard downpipe and middle section but with an aftermarket backbox that you can look straight through.

[pug_ham 244 3 Cars]

Standard GTi Bosal backbox.

That might explain it, there was a topic recently about how the Bosal backbox gives a noisier exhaust compared to some other non oe ones. I found this on my mums 1.6 auto.

 

My 405 is loud and boomy. Standard downpipe and middle section but with an aftermarket backbox that you can look straight through.

You explain exactly why yours is boomy, we are talking about standard exhausts here.

 

Graham.

[welshpug 1,661]

my full aftermarket system is as quiet as a standard one on my 405 Mi16, it has fairly large silencers just like the standard systems just made from stainless steel and freeflow silencers.

[KRISKARRERA 2 1 Cars]

That might explain it, there was a topic recently about how the Bosal backbox gives a noisier exhaust compared to some other non oe ones. I found this on my mums 1.6 auto.

 

 

You explain exactly why yours is boomy, we are talking about standard exhausts here.

 

Graham.

I know, but there's talk about fitting a 405 backbox to his exhaust, so I felt it was ok to talk about my 405 exhaust. Anyway it would cease to be a standard exhaust if he fits a 405 backbox. Maybe the length of the 405 system partly accounts for it's quietness.

[pug_ham 244 3 Cars]

I know, but there's talk about fitting a 405 backbox to his exhaust, so I felt it was ok to talk about my 405 exhaust. Anyway it would cease to be a standard exhaust if he fits a 405 backbox. Maybe the length of the 405 system partly accounts for it's quietness.

IMO it would still be a standard exhaust because no part of it would be aftermarket performance orientated if Eammon was to use a standard 405 Mi16 backbox.

 

Graham.

[B1ack_Mi16 67]

Agreed, the volume is very important. But don't take freeflow dampers (the ones you can look straight through), those are really loud!

 

Also I wouldn't discard the center silencer, it makes alot of difference...

 

My point was actually that with the correct size of these "straight through" silencers the exhaust might be 100% silent and completely free of boomyness...

 

The one in the middle of these (with the very ugly bend on (still making 260bhp though)) is 2.5" size with the largest silencers I could manage to fit.

 

This exhaust is 100% silent and I can't almost hear the exhaust at all when idling, even though it's running race camshafts with like 3-4mm lift @TDC on both cams.

 

Go figure..

 

I built almost the same system for a 1.9 Mi16 once but with halft the length on the middle silencer and also little shorter rear silencer and that one was _very_ boomy and loud.

So get big silencers