Is There A Maniflow Header/quiet Exhaust Combination?

[Puglav 0]

Hi All,

 

I'm getting my cylinder head modified by Brett Sims, ex-Longmans cylinder head man, and he recommends I free up more power by using Maniflow headers and free flow exhaust.

 

Trouble is my only experience with non-standard exhausts was the Magnex my 205 came with when I purchased it a decade ago. I binned the exhaust after six months because it was way too loud for me, going back to a standard original exhaust.

 

Forgive me if this is a daft question, however does anyone know of a quieter free flowing exhaust that can be fitted? It doesn't have to be factory noise, just not "waking the dead" sound.

 

I've seen that DES Developments produced a Group N stainless exhaust - does anyone know how loud these are compared to the Magnex and standard systems?

 

Thanks in advance.

 

Rob.

[GLPoomobile 958]

DES are no longer around and their system was made by MIJ I think, but anyway, I have their single box system on my MI and it's louder than an Essex teenager at the cinema. Don't go there.

 

You probably need to go custom and get 2 of the biggest boxes that they can squeeze in to the space.

[Miles 331 1 Cars]

I'd stick with std or Magnex, Maniflow manifolds are generally mild steel and of course rust (think they would do a stainless one) but Brett will always recommend them much like I do with my exhaust man, All the maniflow systems I have seen are quite loud unless custom, Bullet centre box and larger rears is what you get, I tend to use the largest centre box you can get to keep the noise down, Mild is quieter than stainless too.

If std then the centre split is very important in the Downpipe, without this and you loose top end power

The old Magnex manifolds are good, A friends race car has around 220bhp with one of those fitted so it cannot be too bad.

[Puglav 0]

DES are no longer around and their system was made by MIJ I think, but anyway, I have their single box system on my MI and it's louder than an Essex teenager at the cinema. Don't go there.

 

You probably need to go custom and get 2 of the biggest boxes that they can squeeze in to the space.

 

Interesting, I've used MIJ twice before and like their systems.

 

One of those exhausts was for the 205 - in a moment of madness and after having previously got rid of the loud Magnex, I specified a "louder than standard but not too loud please" pipe...six months later it appeared on eBay. You'd think I'd have learned...

 

I'd stick with std or Magnex, Maniflow manifolds are generally mild steel and of course rust (think they would do a stainless one) but Brett will always recommend them much like I do with my exhaust man, All the maniflow systems I have seen are quite loud unless custom, Bullet centre box and larger rears is what you get, I tend to use the largest centre box you can get to keep the noise down, Mild is quieter than stainless too.

If std then the centre split is very important in the Downpipe, without this and you loose top end power

The old Magnex manifolds are good, A friends race car has around 220bhp with one of those fitted so it cannot be too bad.

 

I think of most straight through exhausts as getting rid of the middle box - if I specify a large centre silencer isn't that going to simply restrict the flow again and be counter productive? Or is it the case that the exhaust being a bigger diameter it still flows better than the standard pipe even with a big centre box?

 

The blurb for the 205 headers on the Maniflow website states that it was designed in conjunction with Longman so I'd still be inclined to go that way what with Brett Simms doing the work - do they rust out badly though or just look untidy with surface corrosion? If so could heat wrap be a solution?

 

I can't find a Magnex manifold for the 205 on their website - are theirs stainless steel?

[welshpug 1,661]

yes, though I doubt they make them any more, there's many other brands doing up to date replications of them however, with a better flexi joint in them, typically found on ebay, works very well to be fair.

 

The mild manifolds will rust out eventually, how long that'll take is hard to say, but they will be a little quieter than a stainless item, heat wrap if anything will make things worse as it'll retain moisture around the outside.

 

when in good condition the magnex exhausts aren't too loud, but they have a tendency to blow the baffles or wadding out of the middle box.

[Biggles 65]

I've got a custom Maniflow system - twin 'straight thru' boxes (centre box looks like a very long cherry bomb but is a proper absorption silencer) - regularly gets 92dBa on 0.5m exhaust test. I think it's probably a case of people who fit aftermarket systems like to hear where their money has gone - mine was for a competition car so I wanted it quiet enough to pass the noise test with a good margin.

I know what you mean about ambarassingly loud - my GSXR had a Micron race pipe on it when I bought it - I rode down to see a friend who lived off the Fosse Way - when I arrived he was standing out in the yard waiting for me - he'd heard me coming 5 mins before I got there !

[Simes 248 2 Cars]

I've got a mild steel one.

Had it ten years.

It's ok still.

[Miles 331 1 Cars]

The box's are straight thou with the old sound deadening around them so flow is fine, Same system on my 306 and that's over 250bhp, Never heat wrap a mild manifold as it scales (Scab's of rust) in no time at all, same goes with systems, better off with a decent coating on them but that just as much as the manifold itself,

 

But a good OE spec system is fine as proven in many a dyno test, My 205 collector friend spent £1000's on manifold design and Engine dyno time and the results where never huge, mind this was 20 odd years ago.

[Lukespeed 10]

Iv got a sportex 2 1/4 road rally system on my 1.9 gti, considering it is completely stripped with absolutely no sound deadening etc, cruising at 60mph you can comfortably talk to your passenger without raising your voices (but in Yorkshire we do talk loudly..) but on the other hand on full chat it does tend to be rather loud

[Mac Crash 78 1 Cars]

It's a case of not being able to have your cake and eat it if you want a full power exhaust, always wondered what the std exhaust system might be like with a tubular 4-1 manifold though? WP mentions the Magnex 4-1 with the flexible joint, there are two types, one with braided steel and the 2nd type which is a solid flexible cup with springs, the latter being the best type.... have the full Magnex system on both my cars, on the 1.9 the power increase is significant and very noticeable, unfortunately, so is the noise.

 

Have seen a lot of the 4-1 systems but nothing matches the quality of the Magnex, sadly no longer in production, remember buying the system back in the early 90's and it was in excess of 400 pounds then, which was a fair wee bit of cash for an exhaust 25 years ago... as always, you pay for what you get...

[Puglav 0]

Well, for better or for worse I've ordered the Maniflow fast road manifold now. I appreciate all different feedback here, however as Brett is doing the head and he recommends matching to the Maniflow (according to the website it was designed in conjunction with Longmans) I'm going with it.

 

I spoke to MIJ who can make up a stainless exhaust to match. They can fit a 4" or 5" centre silencer so I'll go for the larger and quieter 5" to start with. The larger exhaust will reduce ground clearance by 0.5" over the smaller and I had intended to drop the suspension slightly too which is a bit of a concern but hey ho best foot forward.

 

If I lose that silencer to a speed bump then I can go back and they'll fit the smaller 4" silencer instead. They reckon that there's nothing between the two silencers in terms of flow rate, just one has more padding hence quieter.

 

Ps. My GSXR has a Remus loud pipe too, but I love it on a bike - been knocked off too many quiet bikes, could be a coincidence of course...

Edited March 30, 2016 by Puglav

[welshpug 1,661]

get an oval silencer in there, and ask them to add skids, less chance of a hump taking the exhaust off if you do catch one.