Back Pressure & Performance Question

28th February 2007, 08:33

Ok, my Piper 4-1 manifold has turned up and what a bit of kit! The quality of the item is amazing (Should be the price I payed for it).

So the Piper is replacing my Cracked Janspeed 4-2-1 and its got me thinking.

At the moment my current setup is Janspeed 4-2-1 / Sports Cat / Butchered Janspeed Mild Steel Centre section with Stainless Steel pipe replacing the box / Janspeed Mild Steel Back Box Inwardly Rolled 3" tailpipe

Now Im think of having a custom exhaust built when I fit my Piper and Im looking to have S/S straight through system to a S/S Back Box with a 2" tialpipe.

Would this increase the back pressure in the exhaust system there by increasing performance? or Just bottle all the gases up?

My Janspeed looks like its seen better days plus its beging to rattle possible baffles not sure so its a good excuse to look into a new exhaust. Also Im having to wait till end of March for fitting as me and the missis are going on holiday in March and it just makes more sence to wait (plus I can saze abit more money too)

I have a brand new Jap style 3" can (very Compact) sitting around but I feel this could harm back pressure as its simply a straight through style can - Is this correct as well?

Not really asking about peoples views on style just the performance of the two types mention

Thanks guys any help is greatly and welcomely accepted

28th February 2007, 11:38

Anyone?

Ok I'll make it simplier:

Is a smaller tailpipe (OMP S/S style 2") better for performance than a Stright through can (Jap can 3" Straight through)

So really this Exhaust (STYLE - Not OMP as Im not Payin £300+)

Against the same setup as above but with this rear can instead . . .

(The can has a 3" tailpipe so the can body can only be about 3.5" diameter so its not a monster can really)

Just would like some advise on the perks of back pressure created by a smaller tailpipe compaired to a larger tailpipe

28th February 2007, 11:43

Yes of course it is ^

But its not the tail pipe its the backbox.

28th February 2007, 12:06

Quote:

Originally Posted by riggsy

Yes of course it is ^

But its not the tail pipe its the backbox.

Yep I do agree it is the backbox that creates the back pressure but the small exit most aid the increase in back pressure - musten it?

Basically Im looking to have a custom exhaust built to the style of the omp so do I ask for the small 2" tailpipe to aid back pressure as the cans probally would be the same for a larger opening/tailpipe

28th February 2007, 12:11

I honestly dont think the tail pipe makes much difference mate!?

What i do know is anything less that a 3" tail pipe looks abit stupid on a saxo, imo anyway...

28th February 2007, 12:18

id like to know this too?

surley it would increase back pressure?

28th February 2007, 12:46

Quote:

Originally Posted by riggsy

I honestly dont think the tail pipe makes much difference mate!?

What i do know is anything less that a 3" tail pipe looks abit stupid on a saxo, imo anyway...

Yer I agree a bit but Its more to fit the overall look and style of the car as the exhaust Ive got at the moment is more street tuning and Im looking for the rally theme

Hence im looking to go back to a standard grill, striped interior, rallye rims and mud flaps

not everyones tastes but I want the total look

1st March 2007, 09:31

Im gona have a word with a custom exhaust bulder to see if he can build an exhaust to the style of OMP and also see what his opiuns are on the fact before I go on hoilday near the end of March