david

From looking at the dyno page and reading various posts, it appears that a mid-section is required to benefit the gains from installing a downpipe (which will be my next upgrade).

On an Sti V there is no cat in the mid-section, so what are the differences between the PE and SS mid-sections when compared to the original STi V mid-section, and how does it improve the performance?

Cheers,

Dave

R19KET

David,

I have seen results from the SS mid pipe (standard with box cut out and replaced with straight pipe) and also the Magnex, which I use.

All the cars that I've seen, have gained in low, and mid range torque/bhp.

Mainly due to better gas flow.WELL worth the money IMO.

Mark.

R19KET

My STi4 didn't have a centre cat in, but had the small 'mid' box.I only found this out when changing.Nearly put the original back on, to save the £100 odd pounds, but thought what the heck.

So even though my car DIDN'T have a centre cat', and was already straight through, the Magnex made a fantastic difference.Hodge had very similar results on his car.

I can only assume that the centre cat'/box is restrictive.My before, and after runs (same day) are on Paul Strongs site.

Mark.

david

Cheers R19KET, but I was wondering if someone could give a more technical description of how the mid-section improves gas-flow.

Also, after having my car tested for knock on the PE rolling road (I got the all-clear, running rich), would the addition of a mid-section and downpipe alter the fueling in any way?

Stef

David.

I'm no boff' either, but as far as I'm aware, the centre pipe is just that, a pipe with nothing in it. I looked at one on an STi, and could see nothing unusual about it.
Unless it had been changed already, I'd guess there was no real difference from the SS one and a standard STi one.
Probably completely wrong though!

Stef.

firefox

Howdy...

On some cars the centre pipe has a secondary cat in it... and this can cause a little restriction... Hence some people replace the centre pipe for a striaght through one

I have a centre section with a resonator fitted (free flow) to minimise tail pipe noise...

J.

alistair

firefox,

where did you get the resonator from ? I'd like to put a centre section in, but I'm already at my personal noise limit with a downpipe and back box.

alistair

Steve Howat

Hi.

Mid-sections are o.k. but does the small increase in power justify the increase in noise? I had to refit the old section to make the car "driveable" and to enable my hearing to work again!

Steve.

P.S. anybody want to buy a ss midsection??!!

david

Thanks for all your replies. It looks like the mid-section is simply to remove the cat (if there is one) and thus aid/improve gas extraction. Cool.

The SS mid-section is simply the original,UK or STi, with the cat or box removed respectively.

By the looks of the dyno comparison of R19KET's Sti IV the SS mid-section does improve low down (comparatively) bhp and lb/ft over the original STi mid-section even though the original has no cat.

A couple more questions for you good folk,

Steve, what car do you have?

I had a SS downpipe on my old Scooby (MY98) and the noise was awesome, does the mid-section really make such a difference (increase) in noise on an STi?

Is there anyone going to Donnington with the full SS system on an STi IV or V who would be kind enough to give me a ride? I've already blagged a ride of PC (hopefully!)

Can anyone answer the fueling issue?

I followed PC up to Leda a while back, and I must say, the noise (or should I say tune ) coming from his car was incredible. This I think, was with the full system.

Cheers,

Dave

Darren Soothill

The STi V's dont have a center cat in them but it has been found that the 2 box center pipe that is on the car some how seems to have a negative effect on low to mid range torque. The only thought is that there is some sort of resonance being setup by having the silencers there.

Removing these silencers and making the center section straight through seems to add around another 10lb/ft of torque to a standard ECU'd STI at peak torque and seems to make bigger differences lower down from all accounts.

Changing the exahust center section should not affect the fueling but there seems to be some mystery as to why the center section makes such a difference when it is straight through.

I am just waiting for PC to have a center section available and the time to fit it.

Darren

david

Cheers Darren. Are you going to Donnington?

david

Steve,

Did you get my email re: SS-mid-section?

Dave.

MorayMackenzie

For anyone interested, I think PE have now finished their catalytic mid-sections. So, in theory, now you can have your downpipe and mid-section and MOT all at the same time.

Moray

NeilR

Will finally be fitting a SS mid-section to my STi III in a couple weeks time.

Will have to wait until the Dyno day in December to see whether it's made a difference.

Like Mark A. my centre section has a small box in it. Im not sure whether there is a Cat in their or not.

Looking forward to seeing the results on the monitor at PE.

NeilR

Steve Howat

Hi David

I'm not in the office today so I haven't got your E-mail yet. I will be back in on Friday so will read it then.

In answer to your earlier question, my car is a MY95 UK spec car (with the bigger turbo) with ss downpipe and backbox and ITG filter. I shall soon be doing the PE remap and this will (hopefully) be the limit of my performance enhancement.

Cheers.

Steve.

MorayMackenzie

NeilR,

My STI III V-Ltd doesn't have a cat in the centre section, just a smallish muffler box.
My previous car, a 96WRX didn't have a cat in the middle either. Just in case you're interested.

Moray

sonu

Got a Magnex mid-section fitted yesterday at Elite . I don't find the sound increase harsh. Combined with the Magnex backbox, there is a lovely low down rumble produced.

My car seems more responcive now. I'll be taking it to PE for a run.

Thanks

Sonu

david

Thought I'd find out what all the noise was about ( ha, ha) and have a SS mid-section fitted to my STi V before a downpipe.

The results are very favourable, a little more punch mid-range (I hope to find out how much at the next PE dyno day, if we are still going ), the pick up is slightly better, and the exhaust note is now pure <B>SEX!</B>

[This message has been edited by david (edited 13-11-1999).]