decatting a 306 hdi

[Laney9510]

i know im posting alot but im new to this and wanna get my car done , i have heard about decatting the 306 by cutting the cat open removing the plate and welding it back up. the problem ive got is that ive been told if i decat it it will go into limp mode due to lack of back pressure? is this true or can i go ahead and decat it?

[vlj]

No it's not true. Decat it.
You'd be better off buying a straight tube from ebay or welding a pipe through the middle of the cat though.. as you'll never get all the crap out the oem cat.

[Laney9510]

oh okay thanks, but im trying to stick to a budget at the moment so i can keep my money to sort out the whine from my fuel pump:L, wouldnt the inside be the same as any other car, ive done it to a mazda mx5 and the was just a big white block, wouldnt it be the same in my cat?

[ADV_93]

You can buy a tube that bolts straight on... Should help the turbo spool a bit earlier too

http://www.ebay.co.uk/itm/Peugeot-306-2-...43bca28fa5

[vlj]

oh okay thanks, but im trying to stick to a budget at the moment so i can keep my money to sort out the whine from my fuel pump:L, wouldnt the inside be the same as any other car, ive done it to a mazda mx5 and the was just a big white block, wouldnt it be the same in my cat?

If your going to do that, cut the side of the cat open, remove it all like that then weld it back up. Trying to bash it out with a tube won't work

[Laney9510]

if i cut it open and remove the insides and weld it back up it will give the same response as a decat pipe yeah?

[vlj]

Indeed

[Laney9510]

Indeed

thanks

[Jonny81191]

Indeed

thanks

Not strictly true, the empty box will act as an expansion chamber, slowing the gas velocity and therefore increasing back pressure. But it'll still be an improvement.

TBH go to your local exhaust place and ask if they have a bit of pipe you can have, then just cut the whole box out and weld the pipe in instead.

[procta]

I have to say I noticed a massive difference in the cars performance, since I decatted my HDI. the car revs more freely and pulls better too.

[Poodle]

What Jonny said. Try having a look in the guide section, there's a guide for this too.

[ADV_93]

Or grind it off and weld in a piece of pipe the same length

[Dum-Dum]

what youve been told is rubbish

[puglove]

You can get 1m of pipe of ebay for £10 , cut the cat out and weld the pipe in,

leave the mid box then remove the back box and you winning

This is standard cat with the box cut out (and painted)

   

Then my mid pipe/box with the a straight pipe in place of the back box (looks long because its an estate)

   

[Poodle]

what youve been told is rubbish

Hahah we've tried telling him this, don't know where a lot of newbies are getting their info.

[Laney9510]

okay sorry about the 1000 questions just new to the derv scene

[Dum-Dum]

I think alot of die hard petrol tuners spout shit about diesels to look knowledgeable or to put people off diesel as they are scared of the power

[Matt]

I think I need a welder, Jamie your exhaust looks pretty win

[Poodle]

okay sorry about the 1000 questions just new to the derv scene

Don't be sorry for asking a question mate, how else are you meant to learn anything. The banter here is a bit robust, it's not meant personally.

Dum-dum has a point though, whoever told you that hasn't got a clue, maybe bear that in mind next time they give you a bit of advice or "useful" information.

[Laney9510]

Yeah thats true thanks mate id rep u if i knew how, haha.. Yeah obviously he hasnt got a clue but thanks for the advice and ill be sure to get to the job soon

[Daniel-mcgowan]

I replaced my exhaust to a straight pipe de-cat noticed quite a difference and doest seem to be having any problems