GMcM

All,

I've a standard MY99 UK Turbo, and am considering going for a full decat and I've got a few queries.

Does the ECU need remapped or not after? I know it will have to be altered in some way because of the lack of Cat Converter(s).

Will I need to invest in any other hardware i.e. a knock link sensor?? Or is it a safe enough mod?

Is it easily reversible i.e. come MOT time.

Which system should I go for i.e. HKS ??

How much performance gain can I expect? And is it really worth it?

Cheers,
Geoff

john banks

Not on this model, no, yes, yes centre section replace, any that you like the sound of, driveability improvement rather than oodles of power, yes.

7 Foot

The Boy

Do yer really need Knocklink for just a decat???

Nick200

You dont need one, but saying that, even standard or slightly modded cars would benefit.
You just never know..

john banks

No.

I didn't get my yes and nos out of order did I ?

Kingsize K2

John,

IYO does an STi5 require a remap if it has a full decat

Kevin

john banks

Yes or a knocklink, boost gauge and octane booster.

Kingsize K2

In the pipeline!

Thanks

RON

Geoff,

DO get it done,


DON'T moan when you get more power and want to drive the car more!!!

GMcM

Ok, so from all that - I think John are trying to say it is advisable to go for a knocklink sensor when going for a full decat. Yes?

As far as the exhaust system goes, what would anyone recommend? I do alot of motorway miles so I dont want something that is gonna be too loud/annoying during constant speeds.

Cheers,
Geoff

john banks

No Geoff not on yours. Forgive the brief answer but there were rather a lot of questions which have all been answered in great detail repeatedly in this forum before, so I replied to be polite, but kept it brief!

glen4

I have a magnex resonated centre and back box, with a TSL open neck downpipe fitted to my 2000MY turbo, it sounds real nice, gives good power increase and doesn't drone at all on the motorway. I find the complete scoobysport systems too loud and a bit boy racerish (IMHO of course)

glen

Lan Man

Definitely dont go for HKS, if you're concerned about noise levels.

I had a HKS Hiper centre and bb, on a ss downpipe, and it sounded like a cross between a harley and a helicopter.. nice, but a litle too much sometimes.

So now I have changed hks for ss centre and bb, still full decat, but def quiter than HKS.

LM

martin850

iTrader: (51)

I have gor an hks hiper myself and am loving every minute of it. The sound is awsome and hopefully I have got a de-cat scoobysport down pipe on the way soon so it should sound even better.
I know this is boring but would I need a re-map when I get it fitted onto my MY95 wrx import? It does smell like it is running rich at the moment.

markwild

I've a full TSL system on my 98MY UK Turbo. I've not had any extra sensors or ECU mods, so I'd agree with John's comments [ THOUGH, I would be mad not too - but I thought you'd like a second comfirmation ] PS . I do know that the 98 and the 2000 have different ECUs, but....

The system is not too loud on tickover or at marginal throttle needed for 70mph, but IS load at full throttle ...

I've not regretted it, as it makes the car GREAT!

John, Do you think that an ECU upgrade is going to give me much more ? (I've TSL full decat and ITG Panel (engine wise))

If so, what do you suggest ? (and how much diff )

Cheers,

Mark

john banks

I think you could get substantial gains. Suggest speak to BR Developments.

markwild

Cheers John...

Mark

DaveR

... all interesting stuff.

But does anyone know what to do come MOT time? Surely the cars won't pass emissions with full decat - do you have to fix your old centre sections back in or what?

cheers
DaveR (MY02 WRX decat centre and back) <-- considering the full works!

Andy McCord

Dave, spot on your car will fail an emissions test with no cat, although there are a few on here who claim to have got through with no cat, refit centre B4 mot & make sure you thrash the **** off it just before emmisions check (stinky hot), heard tales off the centre cat only just getting you through though as out off the two cats its too far down your exhaust to be as efficient as the D/P Cat (heatwise)

Im like you at the moment still got D/P cat fitted but the more i read up on the benefits off removing it the more im tempted

DaveR

cheers for the reply Andy - more or less what I thought

what about MoTEC/EcuTEK remaps though - are they worthwhile if you leave the D/P in place? - ie. so the car would pass an MOT without being 'fixed'. Do ECU remaps give good performance gains if you leave the downpipe in situ?

Lan Man

Speaking form personal experience.

I had scoobsport decat downpipe, and HKS centre and rear.

Put standard mid and centre section in boot, drove to see my local exhaust man (Raz @ Maidstone exhaust - very very good, for anything a bit unusual).

He removes HKS centre and bb (as one section), and lays at side of ramp.

Fits standard centre and bb

I go for M.O.T which it passed with the standard centre and rear bolted to scoobysport catless downpipe.

Left mot station, went back to Maidstone exhaust and got the decat put back on.

And all for 25 squiddlys.

LM

Obviously I cannot condone a course of action that will lead my people into war! - doh wrong qoute, but you know what I mean.

DaveR

nudge nudge wink wink and all that?
good plan though

Andy McCord

Dave, removal off D/P is the biggest gain (BHP) you are going to get from removel off any part off your exhaust, the reason I havent removed mine is that being an STi V i really would need a remap & knocklink to make sure everything is sweet, from all reports on here ive been studying either Mr Banks or BRD or scoobysport are some off the places needed to be visited after D/P removal (esp on STi's), AFAIK if youre running a uk scoob then remap is prob not worth it.

DaveR

cool, oh well
all the more money to spend on other mods then

The Boy

Just put my MY99 with SS D/P and Prodrive BB ( OEM centre with cat ) through MOT and it passed with flying colours.......Got it done down a local Subaru dealship and technician blokey told me that he had seen ones fail with original D/P, decat centre and performance bb.
Sorry just thought I'd add to the confusion.

Aztec Performance Ltd

iTrader: (234)

Have full turbo back straight through Mongoose on mine. Sound can get a bit intrusive when driving over 100mls.

Power gains were excellent. Deffo get rid of the blasted cats.

As far as MOT tests go there are always garages willing to turn a blind eye to emissions...so i'm told! Jus don't be afraid to ask. You'd be suprised!

Didn't need a re-map on mine as it runs very well with standard mapping. Loads more BHP and Torque.