Standard Exhaust Question (Cat Or Non-Cat System?)

[Ams 23 1 Cars]

Hello all, I've carried out a fair few searches on these forums (awesome resource! ) before pinning down the fact that I need a standard exhaust to replace the horrendous Sportex frankenstien job my 205 Gti came with. I have a GTi-6 engine with "4903106" Catcams installed with a standard manifold and I've narrowed it down to two choices:

 

Option 1 - Non-Cat Phase 2: http://www.buypartsby.co.uk/details/PEUGEOT/205/1.9/1992/__/79/630186/exhaust-part/ (circa £150 for 2 piece)

 

Option 2 - Cat-Compatible Phase 2: http://www.buypartsby.co.uk/details/PEUGEOT/205/1.9/1992/__/79/630187/exhaust-part/ (circa £65 for two pieces - minus cat section)

 

Now the issue for me is that regardless of what I choose I will have to instruct the exhaust fabricator to knock up an adequate downpipe from the GTi-6 manifold to the centrebox, so Option 1's front pipe will certainly require chopping. However Option 2, the "Cat-Compatible" system, seems to make more sense seeing as it's not inclusive of a downpipe thus no chopping required and it's cheaper overall. However I'm hoping someone could inform me whether there is a difference in the centrebox design (baffling) between the cat and non-cat centreboxes? In other words Option 1, seeing as it's for a non-cat system, will it have superior baffling than Option 2 which assumes a Cat would be in front of it? Also does Option 1 have the downpipe split all the way back to the centre box? I ask because it's unecessary for GTi-6 application therefore making the whole length of the front pipe an unecessary expense (again making Option 2 more attractive). However If Option 1 does indeed have superior baffling and the downpipe spit is only to the step down section I'm willing to pay the extra for it as I cannot stand the boom from 3-4k!

 

Please let me know guys, the drone of the current system makes the car far too embarrassing to drive.

[pug_ham 240 3 Cars]

Miles on here sells converted downpipes to fit the GTI-6 engine in a 205 but I'm not sure how the mate up to the centre box unless you buy a full system to suit.

 

If its possible, you might be able to use one of Miles' downpipes with option 2.

 

The centre box in both systems will hardly differ imo, both will be pretty much straight through with the majority of silencing done by the back box.

 

g

[Ams 23 1 Cars]

Cheers for the info pug_ham, are there any images of the downpipe Miles offers?

[Ams 23 1 Cars]

Ah it's ok I found it : http://www.ebay.co.uk/itm/Peugeot-205-GTi-6-Conversion-Exhaust-Downpipe-/251175545223?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3a7b3aa987 . Thing is I know my exhaust fabricator quite well and it'll work out cheaper if I get him to do it, if it all cocks up somehow though I will get in touch with miles.

 

On the subject I was looking at decats for the 306 GTi6 (to get an impression of design) and unless I'm seeing it wrong some fabricators seem to have an expansion chamber incorporated presumably for scavenging/minimising torque losses?: http://www.demon-tweeks.co.uk/performance/catalysts-replacement-pipes/car/peugeot/306-phase-1-gti-6/1996/2-0-16v/magnex-magnex-decat-pipe-peugeot-306-gti . Is this advisable? If so has anyone/can anyone do the same for an XU fitted 205 or do most simply step down the pipe size to the centrebox ala Miles decat?

Edited June 18, 2013 by Ams

[welshpug 1,622]

that certainly is not a picture of a 306 decat pipe!

 

its just a bent bit of pipe with a flange both ends.

 

[Ams 23 1 Cars]

Ah I see! I seen the pipe above on a GTi6 forum (for sale section) and presumed it may be an "older generation" pipe by Magnex and the one on DemonTweeks was their latest offering. Quite confusing.

Edited June 18, 2013 by Ams

[Miles 331 1 Cars]

The issue with the phase 1 DP is they are far too small and take a fair amount of power, Mind I have sold loads of these over the phase 2 system which really is the one to have at the very least

[Ams 23 1 Cars]

I'm making sure I go for a Phase 2 system, cheers for the info.

[Ams 23 1 Cars]

Thought I may as well conclude the thread for anyone searching in future since I've had the bits fitted already. I ended up going for "Option 2", the exhaust fabricator was able to use the existing downpipe and mate it to the centrebox. The exhaust is exactly what I hoped for, it's nice and quiet when cruising especially in the critical 3-4k RPM zone and the din during idling has gone. It's VERY stealthy. The best part is I can now hear the engine in all it's glory! WOT from low RPM produces deep throaty pulses that transition into a singular wail as the revs climb past 5.5k RPM. Best part is the car has more torque low down and has lost nothing at top end, feels much better overall.

The only thing I admittedly miss is the commuter-intimidating lumpy idle (due to cams) that was VERY audible with the Fartex system. With the standard system this has turned into a timid offbeat chuff. A small tradeoff imo!

[petert 550]

that certainly is not a picture of a 306 decat pipe!

 

its just a bent bit of pipe with a flange both ends.

 

Sorry to change the topic slightly, but look at amature lamda sensor installation. It's supposed to be perpendicular to the flow.

[welshpug 1,622]

Thats a magnex decat...

[Ams 23 1 Cars]

Seems quite a common thing depending on space? The angle on the Magnex bung is presumably for clearance or maybe they buy angled bungs in bulk and install them across many of their products. Whether it's necessary on a GTI6/205 downpipe is not something I know though.

Edited July 13, 2013 by Ams