matth76

Hi guys
I have a hawkeye with prodrive backbox, straight through H&S 2.5" centre section, and PPP, which removed the small 2nd cat on the midpipe. It sounds good but could do with just more of that lovely burble. I was thinking of getting a full decat downpipe (Im fine about hassle come MOT), and then remap to improve turbo spool low down the rev range and importantly improve the low down response which I think is where the standard car lacks.

However an extra bonus would be a bit more noise. How does the noise change, just by fitting the decat downpipe to an otherwise "fairly" standard quietish exhaust system? Does it become much more raspy, or does it release more of the classic burble? Does it make quite a difference? I don't mind if it makes it a lot noisier as I'm beginning to think car needs more noise but curious how it changes the tone etc. I think they only make them in 3" > 2.5" to connect to my standard 2.5" system.

Any issues I should know about - are poorer quality ones prone to cracking? Is it prone to knocking against the heatshield if fitted incorrectly?

Thanks for any info.
Cheers
Matt

scoobyboothy

iTrader: (1)

here's my classic decatted



Although now I have a TSL firestorm on now and this is what it sounds like

http://www.youtube.com/watch?v=KSdak1Z6ekc

matth76

Cheers mate. You can certainly hear the difference in tone when you apply some power (idle sounds similar).. but when you apply some gas there is more of a faint slightly higher pitch noise in the background if that makes sense, which I like, and and certainly makes it sound good. How does your car feel ..is there more noticable response low down?

Wilky0302

iTrader: (4)

Hi

What I found was yes the downpipe does make the car a bit louder... The problem you will have though is that you need to remap the ECU as the turbo spools alot faster due to the standard downpipe is very restrictive compared to a open mouth decat one.

It will put a CEL light on....... and possibly also boost spike (which is bad)

I have put the little cat back on mine so that it is mot compliant but I may remove it next time I take it for a remap when i fit my fmic...

Where abouts are you in the country if nearby you could come and listen to my Hawkeye

hope this helps

Midlife......

iTrader: (2)

OP does mention he's going to re map the car (4th line)

Shaun

DonNedly

iTrader: (10)

Before decat:
http://www.youtube.com/watch?v=e6JFtg8HeHA

After decat and remap:
http://www.youtube.com/watch?v=y3Vuk...eature=related

Its louder, raspier and pops and bangs following decat and remap

matth76

Thanks guys. I really appreciate it. Wilky, I'm in west sussex. My car has the PPP, except now has a Hayward and Scott straight through centre section so is still relatively quiet. Ideally I want to keep the Prodrive backbox as I want to retain as much of the PPP as possible. Apparently the PPP replaces the mid pipe and 2nd cat with a straight through mid pipe, some people say without resonator, some say it is straight through. Anyone confirm for sure on the hawkeye sti what the case is? The only part I've removed is the map which was pretty aweful to be honest.

My exhaust system as it is sounds nice when you rev it but at low rev speed I feel as though I could pass people on the pavement and you'd never know it was a Subaru as it was so quiet. It feels a bit "restricted". Anyone else with the PPP will know what I mean. Just want to open it up a bit hence a full decat might release some of the burble hopefully.

53

iTrader: (41)

You don't buy a decat for the noise. It may make burble a little more audible but your problem is the ****ty Prodrive back box if I'm honest

matth76

No, I'm buying it for the increase in low down response which is where the car lacks. I was curious as to what noise difference is Yes I was thinking the noise is widely determined ultimately by the backbox. Just reluctant to let go of the Prodrive backbox. Plus its actually very efficient (flow wise) which I've been told by a specialist so will most likely keep hold of it, plus I like the subtle look of it, although its not that subtle at 4" wide, but I don't think I'd want it any bigger and I like rolled tips. I personally like it. Just hoping a decat will add a side bonus of a bit more noise, as they did on my old 350z.

jh1

a decatted downpipe will add a bit more burble/sound, though the prodrive back box is known to be rather quiet

matth76

Does anyone have this straight exit, not the angled one, (slash cut) 4.5" tip Hayward and Scott backbox: http://www.haywardandscott.com/subar...t-backbox.html? How does it make your car sound? Is it overly loud, droney even when not on gas? I know it's going to have more drone which is fine. Any pics, especially on a newage? The problem with the 2.5l engine is it has less of the classic burble than the 2.0l, so really need to open up my exhaust a bit more. I agree with above, I'm thinking my Prodrive backbox is holding me back. Although I'm still definitely going ahead with decat but wondered whether I should go for this backbox too at same time since I was there. Thanks again guys.

Dave Y

iTrader: (52)

Dont hold back,say what you think....