Hi all,

Like most of you, I've contemplated modifying my Scooby from some time. Having uprated the clutch and brakes, I turned to the exhaust. I already had a H&S original scooby design backbox and was very impressed with it, but wanted to go futher and replace the remainder of the very restrictive standard exhaust.

Obviously, the cheapest route -and the one that yields the highest gains- is a fully decated system. However, I didn't really fancy the hassle that such a system entails at MOT time with respect to emissions etc... and the thought of driving a car that wasn't strictly road legal didn't really appeal either. I'm certainly not what you'd call and environmentalist, but I like to think that I do have some degree of conscience when it comes to these matters! Unfortunately, as many of you are aware, if you leave the down pipe cat in place you pass the emissions no problem, but don't really enjoy much of an increase in performance

Happily, there is a solution that reconciles performance with emission control: A Hi Flow DP

Unhappily, they usually cost the thick end of £500

Thanks to a member on here, I was alerted to an offer that Scoobyworld are currently running on Hi Flow DPs- basically a substantial introductory discount offer on a new Hi Flow DP. A quick call and a few posts on the H&S Group buy on here later and I'm the proud owner of a Ninja Sports cat DP and a H&S straight through centre.

I had them fitted on Thursday, along with a Knocklink as a precautionary measure. I don't wish to get into the pros and con's of fitting one of these here, let's just say that IMHO it's a sensible precaution, for those of you don't think they're necessary, I won't be too gutted if you think I've wasted my money!

Anyway, having taken a few short trips and two longer journeys, here are my impressions of the difference the new system has made to the car.

Noise

If you "like it when they make a bit of noise, sir" Then you'll love the sound that mine makes now! The H&S backbox made the car sound good by itself: a rumble at low revs escalating into a throaty roar on full chat. The straight through centre section and Hi flow DP have made the rumble at idle notably deeper and more "metalic" for want of a better term. The sound of the turbo spooling up is now more pronounced, but not too much so- it's not annoying- it's quite nice to hear it working, actually. When you open up the throttle the sound is now..... well, lets just say it sounds rather angry. The roar is deeper, louder, and considerably more noticable in the cabin. Now it's not just the passers by who are treated to the flat four soundtrack, the driver is in on the action whether he winds the windows down or not! It really is quite startling, each time you put your foot down, you get a menacing howl from the exhaust; anyone who is nearby will crane their necks to see what is producing the remarkable noise. Yet somehow, despite the extravagant noise, they don't seem to be giving me looks of disapproval or distain. It's loud, but because it's nice, people don't mind so much in short bursts. It's certainly a world away from the kind of annoying racket you get from "nova boi" with his 10 inch fart-o-matic system

Then I went through a tunnel. OMG!! I don't think that my Scooby would now be disgraced by any of the sounds produced by much more expensive exotica. The roar that reverberated of the tiled walls of the tunnel was spine-tingling and irresistible in its ferocity!

There is one down side. The lack of a resonator in the centre section does result in quite a marked compromise in the car's refinement at motorway speeds. I think it would be a bit much for anyone who does a lot of motorway miles, or who wants quiet cruising at high speeds.

Performance

Unfortunately, I'm not in a position to elucidate from experience which benefits can be attributed to the DP and which are a result of the centre section, as I had them both replaced at the same time. However, it's generally agreed on here that the centre pipe provides the noise and marginal performance improvement, whilst the DP yields the biggest performance gains.

Driving out of Xtreme, the difference in the car was immediately apparent. The car is noticably more responsive at low revs. With the standard exhaust, the car felt like it needed a concerted effort to get off the line with any conviction...no more! The car takes off much more crisply and without the resistance that seemed to be present before. The turbo is also spooling up earlier, you can hear it start to work at about 1500rpm and it's starting to get in its stride at 2500rpm, whereas before it was more like 3000rpm. The performance when the turbo is on song is also improved. It's not a night and day difference, but the acceleration seems crisper and stronger throughout the entire rev range. The power at the top end seems to be sustained better now too. Overall, the car seems to pull with more conviction and vigor and the power seems available over a wider re-range.

There don't seem to be any negative effects on the car's smoothness or significant difference in fuel consumption. There is no knocklink activity, so the ECU seems to be handling the change fine - which is what SN wisdom would predict.

Looks

It's under the car, how do I know what it looks like!?!?! Build quality looked very good when it was in the box though...not that I spent much time staring at it!!

Conclusion

If you're thinking of getting a De cat or hi flow cat system, I think you'll be plesantly surprised. As I've said before, it's not a night and day transformation, but there is a notable improvement in the car's every-day drivability and it will -no doubt- provide a good basis for an ECU remap to liberate further gains. The only thing to be aware of is that if refinement is important to you, you might want to get a resonated centre section and a backbox that is not too OTT. Remember, the H&S original design is not regarded as an especially loud backbox, but in conjunction with the other exhaust components is certainly making itself heard now!

Hope the above is vaguely informative/helpful.

Ns04

 

Good read and nice to hear as I have ordered one of the said sports cats myself, due hear tomorrow. Did you heat wrap it or were you advise on this at all as I am considering doing this, as an extra measure. cant wait to get it on to see how it performs with my prodrive centre and back box.

 

Really appreciate this informative thread - exactly the sort of info I'm after as I'm contemplating exactly the same thing - decat or Ninja Sportcat...
Cheers!

 

What year is your classic New_Scooby? I wonder if this ninja DP would fit a magnex resonated centre? Hope it does, then off to powerstation for the remap

 

Yes it does, as I have exactly that - Magnex cat back with resonated centre, and now Ninja sports cat as of last Friday. MY00 classic.

As for the remap, I am currently organising one for Powerstation, and we need one more person to kick it off!!

http://bbs.scoobynet.co.uk/showthread.php?t=492944

So get your name down, as I need that remap

I also agree with the well written review above. Quicker spool and more noticeable turbo noise. Deeper 'rumble', and better pick-up. I already had decatted the centre before had the Ninja fitted last week.

 

good post NS04, makes very good reading m8.

paul

 

great thread mate

 

Excellent write-up there mate, loads of things answered that I'd been pondering in a Karl Pilkington sort of way... Cheers!

 

Thanks for the positive comments everyone.

I went out for a bit of blat last night to test my impressions against the claims I articulated above. The car went like stink through the gears on a twisty section of road last night (obviously helped by the low ambient temperature) A "sprint" was the one kind of driving scenario that I not yet had the chance to subject the car to since the exhaust was fitted. It's definately pulling harder and earlier through the gears and is more responsive when you're attacking the twisties.

On the Downside, the cold mornings do mean that the car is on the loud and side first thing whilst its warming up and yesterday I found out that the nature of the sound can set certain over-sensitive car alarms off so it pays to really feather the throttle when pulling into the drive if you want to stay friends with your neighbours.

Ns04

 

Not long done this myself. Had a H&S backbox and centre for quite sometime but now finally added the de-cat downpipe to match.

Pleasently louder and as mentioned more low down grunt due to the turbo spooling up earlier in the rev range. No unusual activity on the CockLink.

Just wish there were more tunnels round here

Was hoping for a few pops and bangs but I guess it takes a while for the system to coke up a little before you start to get them in anger. Did get a few during a spirited drive back from the Wyedean rally a few weekends back, spurred on by the Evo in front of me and the Skoda vRS behind.

 

Come of the throttle in second and let the engine do the braking and you should notice a few pops!

Ns04

 

Nice post Ns04, was thinking about this kinda mod myself. My exhaust has a hole in it apparently, so that sounds like an excuse to change things will have a go when it gets a bit warmer

 

Newbie here, so first of all hi.

I am thinking of fitting one of these to my P1 along with a walbro 225 fuel pump, upgraded oil pump, remap and a TSL Grp N panel filter-which I already have. I was quoted by Bob Rawle that this alone would give the P1 approx 330bhp and 300lb/ft. Not bad for mods which would cost approx £1200.

 

Welcome aboard.

If you're going to do this on your P1 I'd definately reccomend the Knocklink. P1s are basically an STi 5 which feaure maps designed to run on higher octane japanese fuel- they are just about ok on SUL, but add more air via a freeer flowing exhaust and you may get Detonation. There are quite a few reports of Decatted P1s letting go.

If you're getting the remap at the same time as the exhaust then you'll be ok as Bob will remap the car properly to suit UK fuel, but if you're going to run the exhaust for a while before the remap, I'd suggestyou get the knocklink to be safe. There is a Group by on from Bob's company at the moment.

Best regards,

Ns04