Backbox suggestions

Trondelond

Trondelond

Active Member
I've currently got a full 3" AM Performance exhaust, and it's way too loud for my liking.

I'd like to install a backbox where the OE one was, but I can't seem to find one that fits a 3" setup with the inlet and outlet on the same side, so the exhaust tip will be located where I'm used to having it.

Anyone know where I might get such an item?
 
PobodY

PobodY

Moderators
Staff member
Doesn't cambellju have a custom 3" system with a big backbox on it?
You'd never believe the bore to hear it drive past you.

Pipeworx maybe? I know it's not quite that easy when you're in Norway...
 
Trondelond

Trondelond

Active Member
Well, if I'm putting the outlet on that side, it's no problem at all! It's the intake and outlet on the same side of the backbox that seems to be the problem! :)
 
vss irvine

vss irvine

Well-Known Member
if you put it on the same side it will restrict exhaust gas flow.

they put them on the other side to ease flow
 
Trondelond

Trondelond

Active Member
I know, I was hoping a backbox as big as possible would be a little less restricive due to the radi of the bends. But if it's hopeless to get a hold of anyway, I'll have to figure something else out entirely. Perhaps I can get two smaller ones fitted in line with the exhaust.
 
campbellju

campbellju

Moderators
Staff member
My specification was simple, fit the biggest back box possible in the space. It looks offset to the left in that photo as the next size up meant the angle was too sharp for my liking (Similar to OE/Scorpion).

Putting a silencer in the same space as the mongoose style cherry bomb means you end up with a 6" box that would do very little. The centre box has an effect but when you compare either of my past systems with a back box there is no comparison.

If you want to copy mine, any after market exaust builder should be able to do this. It is only a box and 2 bends connecting to your main system.
 
Trondelond

Trondelond

Active Member
Thanks, I think I may have to go for something like yours, my main concern is noise levels. It does tend to attract unwanted attention from the officials. having the exhaust come out on the "wrong" side will as well, but not to the same extent. :)
 
campbellju

campbellju

Moderators
Staff member
I cut back the hole all the way along and smoothed it in with fibre glass. Sadly you can see the FG got knocked on the drivers side. My solution when I get round to it is just to take it back a 1cm higher.

An alternative is Stu's exhaust which is identical to mine but with a hidden tailpipe like on many modern cars that just points down behind the bumper. You could then just fill in the drivers side hole with FG and no one would know. Very stealthy!

Firing the exhaust outlet down should make it quieter too.
 
PobodY

PobodY

Moderators
Staff member
Ah - that's what I need to do; just cut from one hole to the other and make it look like it's supposed to be like that in the middle... instead of looking like someone had a bash at making a hole with an angle grinder when they were fitting the backbox (which is pretty much the case).
 
red reading

red reading

Active Member
I have 2 magnaflow silencers fitted in the standard cat position and before the subframe,it's tight but the car is quiet and the exhaust exit's on the standard position
 
stumo

stumo

Active Member
campbellju said:
I cut back the hole all the way along and smoothed it in with fibre glass. Sadly you can see the FG got knocked on the drivers side. My solution when I get round to it is just to take it back a 1cm higher.

An alternative is Stu's exhaust which is identical to mine but with a hidden tailpipe like on many modern cars that just points down behind the bumper. You could then just fill in the drivers side hole with FG and no one would know. Very stealthy!

Firing the exhaust outlet down should make it quieter too.
Click to expand...
and you can fit a peeshooter sized pipe in the original position, couple that with a 1.4 badge and the chavs wont think you've got a proper R !!! :thumbsup:
 
Trondelond

Trondelond

Active Member
campbellju said:
Let us in on the secret Trond, we may have tried it already?
Click to expand...
I was hoping to do what I've seen on some MR cars; where the exhaust clears the subframe, I'd do a 90degree turn, install one box, turn around 180degrees, and have another one in line, so I'd have to smaller ones going across the length of the car.
However I seem to have forgotten how precious little space is available.

I'll install the 3" exhaust, and take it somewhere to see where and what I might be able to fit.

Would it be benificial to have 2.5" diameter piping on the backbox? I don't know how much trouble this would cause powerwise, but I'd think it would reduce the volume significantly.
 
PobodY

PobodY

Moderators
Staff member
It's an interesting question; I would have thought that by the time you get to the backbox it's not as important any more. You'd be moving the same volume of exhaust, but it comes out at higher speed (and the smaller exit is less like a trumpet).
 
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