Typical Upgrade Path – Hawkeye Impreza 2.5 STi

[Gambit]

Hawkeye 2.5 litre STi from 2006 – 2007 ….

 

 

 

In std form they are 265bhp give or take and have boost at
about 1 bar peak dropping to about 0.8 bar at the top end.

 

 

 

so… choices  .. (all
based on using vpower)

 

 

 

1. Keep the car std but just remap for more oomph and better
fuel economy.

 

A full custom remap will bring boost in much earlier and
hold higher boost levels for longer but the map will be geared to running much
more efficiently ( which is also more economically) as it wont be possible to
push too much boost with both cats in place. Typically a Green/K&N/Cosworth
air filter and a backbox are fitted at this stage but not essential – the
backbox just adds some burble to the quiet hawkeye exhaust.

 

 

 

With a custom remap on the standard car typically this would
get the car to around 310-320bhp with significant torque improvements.

 

 

 

2. Sports cat in downpipe – plus remove centre cat

 

A full custom remap will bring boost in much earlier due to
the lower back pressure and hold much higher boost levels. The remap will also
aim to get it running much more efficiently ( which is also more economically).

 

Typically a Green/K&N/Cosworth air filter is fitted at
this stage (on top of the sports cat downpipe and exhaust system). A walbro 255
fuel pump is highly recommended.

 

 

 

It is also advisable to change to NGK 7 grade spark plugs at
your next service.

 

 

 

This would get the car to about 340 – 350bhp but a huge
boost in torque figures in the mid range.

 

 

 

3. Fully Decat Exhaust

 

The low back pressure from removing all the cats reveals the
true characteristics of the boxer engine and really sets the 2.5 free. A remap
is needed to bring it under control and stop overboosting that will happen
enormously with the 2.5 engine. The remap will bring boost in as smooth as
possible and most likely get full (and higher ) boost at around 2700 rpm and
hold higher boost right through the rev range. The remap will also aim to get
it running much more efficiently ( which is also more economically).

 

Typically a Green/K&N/Cosworth air filter and possibly a
3 port solenoid are fitted at this stage (on top of the decat downpipe and
exhaust system).

 

 

 

This would get the car to about 350-360bhp on the std turbo
but a huge boost in torque figures in the mid range and transform the way the
car drives on the road. I remember this stage well on my own and it is a
fantastic car to drive on the road.

 

 

 

A walbro 255 fuel pump is essential.

 

It is also advisable to change to NGK 7 grade spark plugs at
your next service (ILFR7H).

 

 

 

4. 350bhp – 400bhp

 

 

 

You may be one of the lucky ones and have a car that wants
to produce power with the std turbo – the VF43 on the std car can get to around
360-370bhp tops but if you want to get to up closer to 400bhp there are a
number of turbo options and rather than list them all here – gimme a shout and
see which of the many turbos around could fit your requirements. There are lots
of suppliers of turbos and they are changing all the time.

 

 

 

The car’s engine, gearbox and clutch (just) can cope with
this power.

 

 

 

It is adviseable to fit a larger diameter MAF housing by way
of a good quality cold air induction kit.

 

 

 

5. Getting to over 400bhp

 

 

 

The std EJ257 STi engine has been taken over 400bhp but
really it is adviseable to swap the cast pistons for some forged pistons at
this stage.

 

 

 

Conrods would also be a worthwhile step if planning on
revving higher than the current 6900 limit.

 

 

 

On top of this, there are clutch options, fmic, headers,
up-pipe and lots of other items to consider such as extra fueling. It can be
very expensive step going to over 400 bhp on the 2.5 and if for the road I
would say that it is not worth doing it.

 

 

 

If you do decide that 400+ is ‘needed’ (lol) get lots of
advice beforehand / look at similar cars that run over that level and decide
whether you really want to chase the big numbers as it becomes a diminishing
return for the money outlayed. In most ways it is just as expensive going for
over 500 as it is over 400 so you may as well make that step  I did – it is fun for sure

 

 

Anyway … hope that is useful. The information was provided by Duncan http://www.racedynamix.co.uk/

This information is provided as a guide and not to be used to argue who's the best mapper

As we're a non biased club   :) Mappers contact details for some reputable mappers:

 

Racedynamix

mobile : 07540 185754

email : duncan@racedynamix.com

http://www.racedynamix.co.uk/remap/

 

 

Scoobyclinc

Tel: 01246 590807

Email: info@scoobyclinic.com

Nether Farm

Stubbing Court

Wingerworth

Chesterfield

S42 6QX

http://www.scoobyclinic.com/

 

 

Area 52 Autosport

Unit 2 Park Court

Park Lane Business Park

Kirkby-in-Ashfield

Nottinghamshire

NG17 9LE

http://www.area52autosport.com/

 

 

Andy Forrest Performance

CONTACT

sales@andyforrestperformance.co.uk

Payments via

paypal@andyforrestperformance.co.uk

Tel

01875 811811

AFP 

Harbour Garage

Port Seton

East Lothian

EH32 0DS

http://www.andyforre...co.uk/4436.html

 

[Tidgy]

Near 400 on standard pistons is taking a risk.

[Gambit]

As said, list of mappers to choose from. Just for advice and a guide [emoji6]

[ZaknStix]

Thanks mate 👍 I'll keep you up dated with what I do 

[BennieD1]

Awesome post Duncan. Currently getting mine forged. Will be heading to you after. 

[Tidgy]

16 minutes ago, BennieD1 said:

Awesome post Duncan. Currently getting mine forged. Will be heading to you after. 

my advice, take it to someone who knows what they are doing.

[BennieD1]

Suggest anywhere? From what I have heard they’re pretty good. But any advice is greatly appreciated 

[Tidgy]

Mapping wise, Andy F is up north, Engine tuner down south, Scoobyclinic midlands. Very few places i'd trust to map mine.