Bar

Evening Gents,

Being a new scoob hawkeye STi owner im seeking some opinions...

I want to get my standard exhaust upgraded, but a few things are tossing around in my head...

1) Decat full system...clearly best for BHP/Torque increase, requires a remap, but, before MOT day.. do I need to get it remapped again before I get the cat back on for the test or? seems like a faff...

2) Performance Cat, Non res centre section and rear silencer...less BHP but no screw arounds come MOT day...

3) MOT day is once a year...I am close friends with the testers, why should I be concerned about all above?

4) What exhaust do I get? Quite like the Subtle look of the Prodrive back box, Ive seen one nearish for 200 notes, or... Hayward and Scott..or Blitz Nur Spec R with baffle in (neighbours) or Blitz Nur Spec RX?

5) Do Blitz Nur Specs look chavvy?

Answers on a postcard...

matth76

No you shouldn't need a remap when you put the standard cat downpipe back on for MOT. It wont run perfectly but it will pass MOT.

Bar

Cool! So do I have to put all cats back on? isnt there like 3? hehe

Tredy

I believe you only need one of the two, but dont quote me on that haha

jura11

iTrader: (7)

No you are need just have fitted first one cat,which is suited in Downpipe.
But you must know,your exhaust have 2.5" and from this you must buy cat back exhaust,which is Center pipe and backbox or you can fit as well 3",but after this you will need 3" to 2.5" EXHAUST ADAPTOR KIT
Something like this

http://www.scoobyparts.com/acatalog/...APTOR_KIT.html


Jura

Bar

Hmm! Good info Jura, so what you are saying is I could go for a full 3" straight through system then come MOT day put the cat downpipe on which has a 2.5" exit but have a 3" to 2.5" adaptor so that the OEM downpipe mates to the new 3" system!

Sounds like a plan... as long as it does pass!!!

Next dilemma is...what exhaust?!!

GezP

iTrader: (23)

You don't need to fit the downpipe cat back on - just the middle cat pipe. Its a lot easier to fit. A mechanic can fit it in 10mins and a novice like me 10-20mins. Changing the middle cat is a lot easier than the downpipe cat and still passes on test emissions.

I've even heard test centres doing it for you for an extra £20

Well recommend you having a full decat, I've loved how its changed the cars performance and is so much sharper and responsive. I've got an Afterburner vortex which is cool but VERY VERY loud. A lot of people on hear say the Nur Spec is a good bit of kit.

Bar

Sweet.. Ill take the quickest easiest option, I guess the main lambda sensor goes in the centre cat? or is there a lambda in each cat..I know that is the case on modern vehicles..

Yes, I know from decatting superbikes the difference it makes! like night and day! I put a full Akrapovic carbon system on my crossplane R1 and the front wheel was lifting in the higher gears! Madness... Id like to see just how much of a difference it can make to a turbo....

What is the most neighbour friendly full system to go for? and what gains would i get approximately? currently sitting at 296.5 unmodified!

jura11

iTrader: (7)

Without the remap you will see just smaller increase,but i would don't recommend without the remap on STi.

Here is your exhaust diagram




Not sure,how many cat you have,but i think you have 3.

Best neighbour friendly exhaust will be Miltek,some Hayward and scott,Nur Spec are not friendly..


Jura

GezP

iTrader: (23)

if u like ur neighbours, don't go for afterburner - very loud - but i love the sound it makes

GezP

iTrader: (23)

I don't know about the sensors mate as scoobyworld did it the first time and Tim (mechanic) did it the second time and they've both told me its a doddle.

GezP

iTrader: (23)

hawkeye's have 2 cats. in the downpipe and the center cat.

GezP

iTrader: (23)

that mid-section pipe is just a standard pipe

Bar

Cool, Im getting all the info I need here, thanks guys

Just wondering, what does a prodrive backbox sound like with the rest of the system being straight through? I quite like subtle looks with more growl!

GezP

iTrader: (23)

try and get all the same make/brand mate - they meet up better (thats the advice I got when buying my system)

MRSIMPSON

iTrader: (2)

My old hawkeye, with my old Blitz RX, didn't look chavvy to me

Bar

Aye...would make good sense to hey..

Just been looking at the Hayward & Scott site...

http://www.haywardandscott.com/subar...e-backbox.html

"Centre and back box on its own will give 18Bhp. Complete de cat system will give 25Bhp To fit models 2001 - 2007. Also available in 3" "

For 7 Bhp of difference...am I just worth getting the centre and back!!!?

Bar

Wooooooow! That looks so sweeeeet!

What is it like Db wise bud?

GezP

iTrader: (23)

Don't believe everything you read mate, exhaust bhp figures are always very generous. The biggest difference backbox and centre pipe you'll notice is the sound, its when you start remove cat pipes - thats when the power and response is noticed.

If you change your downpipe to the decated one - heat wrap it too, it dose make a difference

GezP

iTrader: (23)

looks good to me too mate. I was behind another scoob a while back with one of these and the thing was a popping monster, bloody loved it.

Bar

Cheers bud, will get it all wrapped up! the power is what I'm really looking for, 330-340 would be a good figure for me as it will be a daily driver.

GezP

iTrader: (23)

no worries mate, you'll love it when its all sorted

MRSIMPSON

iTrader: (2)

To be honest sometimes I felt the RX was too quiet driving at normal speeds, but it sounds like that's what you're after. And I never had any issues with it annoying me and passengers on long motorway trips. It does sound epic when you blast it though, like a monster.

Here's a couple of youtube clips of someone elses...

http://www.youtube.com/watch?v=QPuBPGqp5oA

http://www.youtube.com/watch?v=XYLuAP1FEDk

I'll try and find the video i made of mine and post it up.

Bar

Out of curiosity...What rough gains would I achieve with putting a Prodrive rear silencer and a 2.5" non res centre Pipe?

(Getting married this year...ive had the purse strings tightened til its all over! haha )

matth76

I've got the Prodrive PPP which includes the rear silencer (backbox), and mid-pipe (the one which connects to the downpipe and contains the smaller 2nd cat) which removes the 2nd cat and replaces it with just a straight through pipe with resonator (although some people say it is a straight through pipe without resonator but no where to confirm this).

I have replaced the centre pipe (the pipe which connects to the backbox) with a straight through 2.5" pipe from Hayward and Scott. It sounds slightly louder but not much. I had a remap by Race Dynamix and my car made 326 bhp and 350 lbs.ft. I suspect most of this is down to the fact I don't have the 2nd smaller cat and the remap releases all the power. If you are after power I'd remove at least one or both cats, and then get remap (you wont see the power without remap and you can't remove one of the cats without a remap as there's a tendency to run lean which is damaging).

However if you're just after sound for now, go for backbox, but the Prodrive is fairly quiet and I'm thinking of going for something which can release more of the burble, so may replace it with a Hayward and Scott backbox ..this one has caught my eye (this is a straight exit slash cut): http://www.haywardandscott.com/subar...7-wrx-sti.html although I've yet to find out what this looks like on a newage or what it sounds like. I prefer rolled tip like my prodrive one as opposed to slash cut like the one in the link. The rolled tip offered by H&S is nice and has a similar subtle look to my prodrive but it is actually a smaller tip at 3.5" tip (prodrive is 4") and wont release any more of the burble than my prodrive (personally I want a bit more sound but not too loud hence I'm considering the slash cut one in the link which is also slightly bigger at 4.5" but that isn't too large and should still look fairly subtle).

But I'm not sure yet what the slash cut will look like. I am like you and only want a subtle looking rear, hence I want it a straight exit as opposed to "angled". Good luck with your search as it is quite a personal choice and I take a long time like you as it is a fair bit of money and best to get it right .