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Quote:

Originally Posted by Johnny Danger (Post 373017)

ST,
I don't disagree with your approach, nor the results of your upgrades. My advice to the OP simply was - adding headers (regardless of who or where they're made) in conjunction with the very restrictive cats on a 2.5. - would be fruitless in terms of increased power or performance. Going catless as we both agree - results in a very noticeable loss of low end torque. In addition, since this is a North American vehicle, going catless would further complicate the process by virtue of our OBDII compliance/emissions requirements.

I think I stated somewhere I thought the biggest restriction was the stock cats.
I think our points may have been lost through the eloquence of our verbiage. :)

Im sure if you ran the full system through cats it would quiet things down a tad as the cats are a resonator of sort.
Probably, well probably most certainly more hassle than its worth.

Not sure how much losing the low end tq would bother me because on these little engines you shouldn't be down there anyway.

So to sum up so far......Biggest bang for the buck here is the CC cat back. The CC headers open a can of worms when considering cats and emissions compliant, a lot of hassle and probably pricey cats for not a lot of return. Can be done and probably does add something to the upper end. Seems quality is pretty good.
Charlie must have some of his best guys laying down the Porsche pipes!

Quote:

Originally Posted by Steve Tinker (Post 373012)

Evomind....
Notwithstanding what JD says (and I remember him going through the same hoops as you a few years ago so yes he did do his homework), I can give you my impressions of the CC (Delubozparts) headers & cat delete pipes - though it's a little different for us with ROW specs with no cats fitted in the factory headers. Plus mine is a 2001 S model with the 3.2 engine with more torque than your 2.5 engine, so if you do move the power band or lose torque by fitting bigger diameter pipes, you will notice the difference very quickly with your smaller engine.
I've had my mods fitted for 2 years and as yet no problems, no cracks, no broken clips or bolts.

1) Che at Delubozparts was very good answering my questions - parts arrived well packed and visual quality seemed good when package opened. Two screw in plugs were missing, but Che posted replacements off immediately. Weight was approx same as the factory headers (remember no cats) so should be lighter than yours.

2) I had no problems removing the original header bolts, but some people have had nightmares with rusted bolts snapping off in the heads but mine were fine. The headers fitted well, but if I were to do it again I would open up the bolt holes slightly to allow a little more movement when fitting the final bolts. You cannot fit the plastic undertray back as the headers are lower than standard.

3) I fitted the headers to the standard system first without the cat delete pipes. Initial impression was a slight loss of low down torque below 3,000 rpm, but an increase in power above 4,000 rpm - much as what Nine8Six commented on above. Sound level was normal up to 4,000 rpm then exhaust note hardend above that.

4) Fitted the cat delete pipes ~1000 km later after welding in threaded boss's for the sensors. Fitting was not too difficult but one pipe is longer than the other so don't go cutting before you check first. Weight loss was approx 3-4 kg from the standard cat pipes.
Immediate impressions were good, with the low down torque now returned plus another little little increase in power above the 4,000 rpm threshhold. The biggest difference is in the sound - a very slight increase in db's around town but above 3,500 rpm it starts to sound really hard - quite addictive. These mods are fitted to the standard rear muffler - no way will I drive a car which has the dreaded drone of most (cheap) rear mufflers.
Seat of the pants is about 10 bhp increase (subjective I know), but certainly more than the increase the UDP gave me.
Bang for the bucks is good (even including for postage to Australia) as Che had the parts on special and I did the install myself. Given the choice I would cetainly buy them again, but I wouldn't purchase the rear mufflers after listening to a Boxster on a local Porsche Club run - how the driver and passenger conversed or how their eardrums took the noise is a mystery to me.....

Good write up!
Getting more air into the engine might help a little with the low end loss of tq.
Also it seems a few more ponies could be had going to a less restrictive cat back system. Based on previous posts, drone was minimal.
That said, if its a car you drive a lot, like a DD or semi DD, I wouldn't want it overly loud either.
Interesting also that you said the UDP didn't do much for you. Some people rave about them in other posts. With all the cars Ive had Ive never bothered with an UDP but the little 2.5 needs all the help it could get. :)
Thanks!

Here...this is pretty loud but it wasn't a DD. No cats! :troll:

https://www.youtube.com/watch?v=yt3GJSVMjok

Get yourself a set of custom T316 stainless steel headers from M&M Exhaust Germany with 2.00 primaries straight through to the catback, along with a set of HJS 200 cell tri-metal cats. It will give you about 15 hp at the wheel ! :)

Quote:

Originally Posted by evomind (Post 373036)

Good write up!
Interesting also that you said the UDP didn't do much for you. Some people rave about them in other posts. With all the cars Ive had Ive never bothered with an UDP but the little 2.5 needs all the help it could get. :)
Thanks!

Don't get me wrong - the UDP is THE best vaue for money bar none.
But it only nets about 5-7 hp or so @ low to mid rev range according to Raby who I bought it from, while the exhaust mods reaped a bit more than that @ the upper end of the rev range.
At least that's how they felt by my bum-o-meter, the only real way is with a dyno of course....

Quote:

Originally Posted by Johnny Danger (Post 373038)

Heck no!
I can get CC 2.25 to the collector then 2 through the cat back out the exhaust!
Come on!
:)

Quote:

Originally Posted by evomind (Post 373046)

Heck no!
I can get CC 2.25 to the collector then 2 through the cat back out the exhaust!
Come on!
:)

Not sure if 2.25 in optimal for a 2.5. motor though. :)

I don't know about you guys but I whacked on an ebay rear silencer, some of the ebay headers and did before and after dyno runs at the same place and showed real improvements from 3-3.5k rpm. I did the same with the 996 throttle body and with a subsequent remap. Granted this is all on a 3.2 rather than 2.5 but the basic principles are the same. Those exhaust parts were so cheap is was rude not to have a go, like £130 and £110. Of course in the UK there is only one set of cats to worry about too.