aftermarket exhaust inside diameter

ihave an 01 650 i. i feel the std muffler is a bit restrictive,after pulling it apart and having a look at the internals
.i,m thinking of ripping the guts out of my tailpipe/muffler and making it a straight through system,similar to the performance aftermarket jobs.
this thing has a 35mm i.d outlet.
can anyone tell me a inside diameter of the outlet of a performance pipe, and the brand of the pipe which you are referring to.
thanks ..weed..

hello,

my doma has about 48mm oulet and the FP about 44mm.

Hopefully this is usefull for you.
Madero

thanks madero much appreciated.
..weed..

Sil Motor Exhaust inside diameters
Perforated muffler tube: 60 mm
Outlet: 58 mm

Sound level < 94 dB

Well, I'm glad you posted this in the lighter side - at least we don't have to take it too seriously now :wink:

But as usual I'm going to be slightly difficult and ask you some questions first instead :wink:

Do you want more power or just more noise?

Do you still have the original 01 exhaust system?

Which silencer do you have right now, the mx or the enduro?

If so the 35mm exit on its own isn't going to be the problem.

If you have the mx silencer, i.e. straight through with reduction at the end, simply adding a larger diameter perf. tube into the silencer will at most give you about 1hp and a lot more noise.

If you have the enduro silencer with the internal baffle and an expansion chamber with reduced exit adding a larger diameter perf. tube might give you something like 3hp.

The biggest problems are in the whole system not the silencer.

A simple update is merely to update your 2001 system with a 2003 or later system as that wil give you better power - around the 55 mark for the system with the enduro silencer or about 56-57 with the mx silencer - not a whole lot in it.

It it's power you're after you need to change the headers and collector/secondary pipe I'm afraid.

As simple update to the 01 system if you don't want to spend any money is to tidy up the original collector internally - you can find a diagram for doing this in my gallery and then having max. 46mm o/d perf. tube through the silencer. You honestly don't need any more.

The reduced exit actually doesn't do a lot in terms of restricting flow on its own but it does do a great job of reducing noise output. In actually fact, having a small reduction in tube diameter can in some case improve exhaust flow because the increase flow speed reduces pressure and therefore helps to "suck" gases towards it
.
Hope this helps,
Simon

thanks simon, i done a similar mod to the headers where they protrude through into the collector box.the muffler is a fe .i don't how its suppose to look inside stock but it goes through a consitena bend then 1/2 way along it gets squished into an oblong then reduced down to 35mm id.
noise is probably not to much of an issue within reason.think i will go with whatever size perforated pipe i can get ,about 43-44mm hopefully.
what do you reckon with that?
..weed..

Hey weed,

It is that convoluted pathway you want to get rid of in the fe silencer as well as the final small expansion chamber right at the end.

Something about the 43-44mm mark should be absolutely fine. You'll get some extra ooomph out of that.

If you're handy at a little pipe work (you certainly seem to be handy with just about everything else!) it would also be worth getting rid of the sharp 45 degree bend just following the exhaust ports.

All the best,
Simon