The following article is some feedback on what must be the cheepest combination of mods for our Newage Scoobies. This is effectively all courteously of the ScoobyNet and the OpenECU.org community as this is where I did all the research...
Below is the order I installed the mods to my standard MY03 WRX along with a little feedback on how each effects performance - both good and bad points.
Dawes Manual Boost Controller (MBC)
- The Dawes was first, as I purchased it for my MY00. It went straight on my MY03 after I'd run it in.
- Dawes was imported (during Nov 2001) direct from 3 Bar Racing (formally Dawes Devices) in USA - £19.50 ($35) including shipping.
- I used the Dawes to slightly increase boost but mainly to improve turbo spool up. Used a Dawes for over 3.5 years now.
- Dawes is set to increase boost by approx. 15% so that it is under the standard fuel cut. You have to set, monitor and adjust boost settings using 5th gear wide open throttle runs to ensure you don't hit fuel cut. For me, 1.1 bar (16 psi) made for good results.
- Car felt much quicker (on MY00 and MY03), especially on my motorway commute to work where overtaking was much improved. Basically you don't need to change down if you are feeling lazy.
- The cars handling is affected as you now need to 'bleed' the power on using the accelerator say round corners or off roundabouts. Some might assess the handling to be a little 'twitchy' but once your used to it you'll learn to enjoy it.
- With the Dawes, i.e. boost not controlled by ECU, the car doesn't run quite as smooth when driving slowly with revs under 3000 RPM. This is only slightly noticeable as passengers would not even notice. My best guess is that the Dawes struggles to maintain a smooth boost profile when using very low boost. I thought about getting one of the more expensive Dawes devices which have a lighter ceramic ball. On the web site it says it is more responsive however I could not find enough people on here to independently confirm it makes any difference in the real-world.
- Back when I first started to use the Dawes there was concern on the Scoobynet BBS with how it operated on part throttle. The main concern was that too much boost on part throttle could lead to lean running. From peoples trials (I was keeping up with John Banks' feedback) it seemed that opening the 'bleed' hole on the Dawes to 1.5mm would help. So this is what I did, as did many others.
- Personally I was also keeping an eye on the boost at high revs in say 4th especially when the car gets hot perhaps waiting at traffic lights. I found that the Dawes seemed to drop a little boost at high revs as it got hotter. This made me feel a little more comfortable as this made things a little safer.
- So Dawes was great for me on MY00 and MY03, as long as you keep boost to a sensible level (under standard fuel cut). When the car gets serviced by the main dealer it takes me 5 mins to remove it and but it back to standard.
Decat OEM center pipe
- Decat OEM center (number 1 in the diagram below) - I purchased a second-hand 1yr old standard OEM center pipe for £25 which had the CAT in. Basically I bashed the CAT out and got my local tyre/exhaust fitter to install it for £10 (whilst replacing my tyres!). Bashing the CAT out of the center pipe was easy, took around 20 mins using a drill, a long handle bladed screw driver and a hammer.
- Why? Well I did this for two reasons. (1) if someone looked under the car, say during a service or MOT, the car would still look standard and (2) because the research shows that what I have done here is as good as an aftermarket decat pipe.
- With the decat'ed standard OEM center pipe now fitted to my MY03 the car sounds slightly different. New age cars seem to have lost the noticeable Scooby 'burble' on tick over compared to my old MY00 classic. Anyway the decat'ed center pipe has brought it back.
- 'Normal' performance doesn't feel that much different. Although the car does seem to be slightly happier above 5500RPM to the red line. I assume it's breathing a little better now. Given that I don't rag the car through the gears every time I drive it I didn't feel this gave much more every-day performance. With that said if I wanted the occasional race off the 'lights then it seemed to be a little quicker because you could hold on to a gear for a few more revs.
- In summary, Scooby 'burble' is back and very slightly better at high revs.
Decat OEM down pipe
- The latest edition is the decat'ed standard OEM downpipe. I did some research on here about decat downpipes. By far the best I found was the thread called Downpipe FAQ on this page. It concludes that what I have done here is as good as an aftermarket decat pipe. The instructions to gut your stock down pipe are here.
- First thing you notice with the decat downpipe is an even better exhaust note on tick over - even with the standard pee-shooter back box!
- You can now hear the 'whistling' of the turbo as you accelerate slowly to 3000 RPM in the first two gears. This is not noticeable above say 30-40 MPH.
- Performance is very much improved. Car comes on boost around 400 - 500 RPM earlier and pulls much harder throughout the rev range.
- The revs now seem to go straight to the red, very quickly. It's dame good!
- Gear changes on full throttle are easier and seem to keep the turbo on boost - less performance drop off between gear changes.
- The car is also really smooth at low revs again. This was a slight annoyance when I fitted the Dawes but its great now.
- This is a strange one, but the car seems to engine-break a lot less now when you are coasting in say 5th gear behind traffic on a motorway. Perhaps related to less exhaust restriction/back pressure?
- This was a very exciting project which saw me remapping my ECU using OpenSource software and a ODBII cable for £45!
- This would make the Dawes MBC modification above redundant as I can now increase and control the boost electronically (read: better) by remapping.
- I purchased an OpenPort 1.2 cable for $79 (£45) from Tactrix and used the excellent free software from the OpenECU.org community called ecuFlash, ecuEdit and ecuExplorer.
- Using ecuFlash I read my ECU image on to my laptop. ecuEdit allowed me to identify and modify the various maps. ecuFlash was used again to reflash my ECU with the new image. ecuExplorer allowed me to perform a detailed diagnostics log of almost anything the ECU can ‘see’
- I’ve written separate articles all under the ECU knowledge base which describe all this in more detail. At the time of writing the author has something equivalent to the power released by a Prodrive map.
STi PPP Back Box
- Found a STi PPP Back Box for sale on Scoobynet for £80 and was perfect as a more visual and audible modification. Can’t say this improved performance at all, only to say that it sounds like a Scooby is supposed to now!
The car is much faster than standard, although not really sure how much power I've gained on paper as I'm not very interested in rolling roads. Performance is anticipated to be slightly higher than a WRX PPP so around ‘’’265 – 275 BHP’’’. Note, my car will not pass an MOT test. I'll swap the exhaust (hopefully center CAT only) when the 3-year MOT grace period is over.
For a little less than £262 (excluding Dawes - as no longer required) my MY03 looks absolutely standard from the outside, however feels and sounds much different. For the cost, you'll struggle to get much better.