Worth changing from 2.5" to 3"?
01 January 2003, 05:01 PM
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I have a full Scoobysport on my STi7.The DP is the 3 to 2.5 variety and the rest of the system is 2.5 all the way back.Now that I've started tuning.ie have Ecutek and will be ordering fmic+/-WI am wondering whether I should change to a full 3" system.The cost will be considerable,ie £250 for the DP(plus 3 hours fitting) and the HKS Drager 2 is £650(Blitz,Hiper will be too loud for me).Will I actually benfit much or would the money be best spent on other mods?
01 January 2003, 06:23 PM
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If you can tolerate the noise then go for it. I am driving about 60 miles a day and a 2.5" Magnex is enough for me noise wise, and sometimes I think about putting a PPP backbox back on. My car doesn't seem to be lacking in top end for the spec and boost I am running, so the 2.5" can't be that bad. Depends on how far you want to take it?
[Edited by john banks - 1/1/2003 6:23:20 PM]
[Edited by john banks - 1/1/2003 6:23:20 PM]
01 January 2003, 08:09 PM
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A complicated noise level comparison (all my own work 
)
Hayward & Scott DP (3 to 2.5"), PE centre (catted & 3" tube with 2.5" 'joints') & TSL backbox is slightly louder than a full 3" BPM DP with HKS Drager.
The Hayward & Scott DP with the Drager is actually quite a bit noisier than either.
The PE catted centre is a good 'silencer' and seems to flow pretty well (going from required fuelling) - there's obviously some restriction, but less than I'd have thought.
Comparing the fuelling requirements of the H&S/PE/TSL (essentially a 2.5" system) to the BPM/HKS one (full 3"), they aren't that far off - so the power probably wouldn't be that much different. There is an increase in power with the BPM/HKS, but not large - the car feeling quite a bit more refined is the biggest change. The engine feels 'happier' (getting technical here).
Now, the BPM DP with a 3" Afterburner is seriously loud (to me) and makes a big difference to the fuelling. I'm guesing this is the 'good stuff' about the Hiper which I've never tried!
Don't know if any of that helps - having read it back to myself I'm now very muddled so I can't see anyone else having much hope!
)Hayward & Scott DP (3 to 2.5"), PE centre (catted & 3" tube with 2.5" 'joints') & TSL backbox is slightly louder than a full 3" BPM DP with HKS Drager.
The Hayward & Scott DP with the Drager is actually quite a bit noisier than either.
The PE catted centre is a good 'silencer' and seems to flow pretty well (going from required fuelling) - there's obviously some restriction, but less than I'd have thought.
Comparing the fuelling requirements of the H&S/PE/TSL (essentially a 2.5" system) to the BPM/HKS one (full 3"), they aren't that far off - so the power probably wouldn't be that much different. There is an increase in power with the BPM/HKS, but not large - the car feeling quite a bit more refined is the biggest change. The engine feels 'happier' (getting technical here
).Now, the BPM DP with a 3" Afterburner is seriously loud (to me) and makes a big difference to the fuelling. I'm guesing this is the 'good stuff' about the Hiper which I've never tried!
Don't know if any of that helps - having read it back to myself I'm now very muddled so I can't see anyone else having much hope!
02 January 2003, 11:36 AM
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HKS headers - the 'usual' seems to be the removal of 6% of fuel at low rpm, addition of 6% at higher.
The car feels much more rev-happy after installation; the engine is also noticably 'quieter' (this is knock-link quiet rather than in-car quiet as the burble largely remains!)
The main thing I think which is good about them is - as you put it gains/losses - I can think of no losses. There is no (noticeable) point at which the headers have 'lost out', but there are obvious gains too (the higher rpm ones!).
I think ChristianR & Tim W have the same headers, as does/will Adam M? All seem very happy with them
The car feels much more rev-happy after installation; the engine is also noticably 'quieter' (this is knock-link quiet rather than in-car quiet as the burble largely remains!)
The main thing I think which is good about them is - as you put it gains/losses - I can think of no losses. There is no (noticeable) point at which the headers have 'lost out', but there are obvious gains too (the higher rpm ones!).
I think ChristianR & Tim W have the same headers, as does/will Adam M? All seem very happy with them
02 January 2003, 01:24 PM
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Deep,
porting standard headers will reduce noise by around 6-8db.
BPM downpipe is around 4-8db quieter than the Scoobysport downpipe.
~~Standard headers, BPM, HKS Hiper = 102db@4000rpm; with HKS Bung, 98db
~~Ported headers, BPM, HKS Hiper = 96db; with bung, 92db
~~Ported headers, S/S (H&S), HKS Hiper = 104db; with bung 99db
Based on real measurements - although different days and at different tracks - same measurement protocol though.
Trout
porting standard headers will reduce noise by around 6-8db.
BPM downpipe is around 4-8db quieter than the Scoobysport downpipe.
~~Standard headers, BPM, HKS Hiper = 102db@4000rpm; with HKS Bung, 98db
~~Ported headers, BPM, HKS Hiper = 96db; with bung, 92db
~~Ported headers, S/S (H&S), HKS Hiper = 104db; with bung 99db
Based on real measurements - although different days and at different tracks - same measurement protocol though.
Trout
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02 January 2003, 02:36 PM
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Deep, have a word with Pat about his own design of exhaust system. I have one, and it made a big difference over the BPM/Magnex/Scoobysport system I had before. It is actually more quiet than before, and we a re fairly sure it will flow better than the hks anyway. I shall not say much more about it here, as that is Pat's place, and I believe he is thinking about having a number of these systems made up, assuming he gets enough interest. I posted a bit more about this on 22b before christmas. Moray
I shall not say much more about it here, as that is Pat's place, and I believe he is thinking about having a number of these systems made up, assuming he gets enough interest. I posted a bit more about this on 22b before christmas. Moray
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