Tiss

I'm going to de-cat my V5 STI type R, just wondering which downpipe and centre section are the best???

Thanks in advance

pappasmurf

Can't go far wrong with Hayward and Scott IMO.
Very pleased with mine.

smurfy.

Mal26

Totally agree!!

harvey

iTrader: (48)

On my STi ver 6 Wagon I am using an open neck 3" Roger Clark Motorsport D/P with Scoobymania 3" centre section (with centre box) and S.M. 3" back box. (Prize from Scooby Shootout winner). I did have the 3" centre section without the centre box but the car was noisier than I liked. That centre section is now for sale £70. What attracted me to this overall set up was that it is a straight through system and is very straight.
The previous system, H+S 3" open neck down pipe and 3" Revolution exhaust system are now on the WRX.
In all cases, headers uppipe and down pipe are wrapped.
I also have for sale a brand new Scoobymania 3" twin dump down pipe. A work of art. £200.

Tiss

Cheers for the replies. Could anyone tell me the difference between a downpipe with two exits on it, one from the turbo the other from the wastgate, and Tsl's downpipe which just has on large opening??

Tiss

BTTT

Tiss

Alrite Harvey, could you tell me what performance differences the twin dump and open neck downpipes have please?

Also which manufacturers would you recommend??

Cheers Tiss

Welloilbeefhooked

iTrader: (3)

And!!! (sorry for the hijack)

What is the optimal bore size for the exhaust?

I have a 3" downpipe going into a 2.5" standard system (I did not do this before anyone starts!!LOL) and have been told that 3" systems are only good on scoobs with 400bhp plus, with a loss of low end torque and spool up (by H&S).

So whats what? Should I be junking the downpipe and fitting a full 2.5" system or going for what H&S have said, leave the downpipe on and run a reducer into a 2.5" centre and backbox?

Any ideas/comments

harvey

iTrader: (48)

If you want power 3" all the way everytime even if you do not. Loss of torque is a myth but unless you want to do other mods to gain more power there is little point changing now.
There are two schools of thought on the single D/P or the twin D/P. I am in the sigle D/P camp but do not have accurate back to back evidence to support that view. I have for sale a brand new 3" twin D/P and centre section slight use from Scoobymania, looks good.
I was running an H+S open neck 3" and now have (by circumstance) the equivalent item from Roger Clark Motorsport. No discernable performance difference.
Basically you want 3", as straight as possible and definately no tight turns, nothing too heavy, well made, look at the welding and bending, no ripples, is clean internally with no constrictions. After that it is how quiet or loud you want.
I expect several manufacturers systems meet the criterion.

Tiss

Cheers for the reply Harvey, How much do you want for the downpipe and centre section please?? Also do you know if it would mat up to a Trust back box?? Would I need to get my car re-mapped when I fit them or are version 5's o.k?

Also where are you from??

Cheers Chris

Welloilbeefhooked

iTrader: (3)

I was thinking of the Scoobymania centre section and backbox, but with the silencer in the centre. How much quieter would this be over the straight through centre? And does this meet the requirements you mentioned Harvey?

Tiss

BTTT

greasemonkey

That's an impossible question to answer accurately without knowing the context Tiss.

If you've already had your car remapped to run safely on UK fuel, the ECU should cope with the increased spool performance and freer breathing that you'll get, although you ideally need the reassurance of a KnockLink to be sure that things are still within safe parameters.

However, if you're running a standard ECU on Optimax (or similar) alone, and without the protection of a KnockLink, you're already a little bit closer to the edge than you want to be, and the decat is only likely to make things worse.

Tiss

Greasemonkey, I already have a knocklink, oil press, temp and a boost gauge and run on optimax and octane booster, but have been told with it being a version 5 STI then it won't need mapping straight away??

Tiss

BTTT

greasemonkey

There's no certainty with things like this Tiss. If you're lucky it won't need a remap, but don't take this for granted. Keep a close eye on the KnockLink and boost gauge and see what happens.

Tiss

I will do Greasemonkey, would you recommend fitting an AFR meter aswell?? If yes which one??

Thanks

greasemonkey

Yes, it certainly won't do any harm. Fit it before you change the exhaust system so you'll get an idea of what the AFR's should be, and so you'll be able to spot any changes post the mods.

TBH you can make a perfect AFR meter yourself for less than £10's worth of bits provided you're up to a bit of soldering and have a digital voltmeter for calibration. If you're talking about the commercial ones, the Dawes "Subaru specific" meter is the most useful.

BladeRnnr

Right..what to go for magnex twin down pipe and stright thro' centre...But with a difference..

Find a place called ceram coat/cam coat..its in warrington..spend about £80 -150 and have them ceramic coat them inside+out...!! (only on new pipes!! tho)

this aids flow and reduces underbonnet air temps...cooler = more power..(can go into half page on why but i can't be asked..!!)

any body wants to question the coating...Jaguar lemans winners..X years back had there exhausts coated..!!

Next if you have a pwer cone etc...get rid put the old air box back with a k+n filter but go into the wing (have to remove wheel to do it) and remove the air resonator chamber..that way cold air free flowing from wing..and no heat from engine bay..(these are bloody good mod's on cheap..)

I've been running uk my 2000 like this hardly any drop off of torque (i.e. flatline which is torque all the way to redline...last time i looked this held its torque better than most of its age..!!) and 270 bhp(bit more than on graph..!! ;0)
..Not bad for only£400 .....
http://dyno.scoobynet.co.uk/WLuk/mike_ferries.htm

m.