Going to fit a decat downpipe to my sti4. Heard different things from different people regarding the need of a remap.
I've been told that it may cause the turbo to overboost, however, ive always understood that a wastegate is there to stop this from happening??? Would appreciate advice as ive been given very different advice from 2 very reputable scooby specialists. (Not dealers)

 

anyone???

 

From what i have been told it causes overboosting & causes No3 Cylinder to detinate causing BANG

 

Do you have a Knocklink? That'll soon tell you if you need a remap. There's a group buy on right now if you don't.

 

IMO,a knocklink is compulsary as mentioned above.

You will probably find that you are getting det even without changing the downpipe,especialy if youre not adding octane boost to your super unleaded.

Changing the downpipe will cause more boost and the ecu will not be able to compensate (its probably having a hard time already as its mapped for 100 ron fuel).

You will probably feel that the car is driving perfectly and accelerating very well,but this does not mean it is neccesarily working within a safe limit.

To answer your question,a remap 'is neccesary' in order to run on uk fuel safely.remapping will probably increase the performance aswell as reduce fuel consumption or at least make the the throttle response better,but this is dependant on the quality of remap.

Andy F and Bob Rawle are possibibly the best people to speak to about mapping but bear in mind you will need a good £600-£800.

You can get away with 98ron fuel and OB but this can be a bit of a pain at times.

Bottom line is,get a knock link fitted before you go any further (unless you already have one).

 

I ran my STI4 for 2yrs with HKS down pipe and no remap without any problems,

Boost rose 0.1 bar and still had no more knocklick activitey than it did before and i never used octane boost unless doing a trackday,had link fitted now though.

Not saying this is the case for everyone.

 

I ran my STi 5 for a year with a straight through HKS system and an induction kit,no knock link,no OB,but did use optimax.
Serviced regularly with Mobil 1 oil,warmed up and down,thrashed the living 4uck out of it for 11,000 hard miles,never had a problem,loved it to bits.

One day it developed a knocking bottom end (this is very rare in Subarus according to many specialists).

If I had sold the car before it happened,I would have been one of the people who would have said 'a remap/knocklink/OB are not neccesary'and the next owner would have been saying 'these engines are made of 5hite'.

Best to be on the safe side and get a KL first and then you can check wether or not your getting det.

my tuppence worth

 

How do I get involved with the group buy on a knock link???

 

And if it is going to overboost, what is the waste gate for???

 

Is a remap necessary?

Yes!

Screwd.

 

Knocklink group buy thread

 

I have put a 3" downpipe on my STI 4 RA today, I am using dawes to control overboost and seems to work ok and keep knocklink activity down. However a re-map is by far the best option. I'm saving my pennies

 

How much does a remap cost and is there anyone in the south east that can do it

 

http://www.powerengineering.co.uk/

 

Power engineering have already told me that they are not prepared to remap my car as it is an sti 4 and apparently are prone to having engine problems, even though any problems would have come to light by now. (65k). That was 8months ago though, they might now, ill ring in the morning

 

For an STI 3 or 4 this is your best option -

http://shop.scoobynet.co.uk/Product.asp?ProductID=1063