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Discussion Starter #1
Guys
Having introduced myself earlier today, I am keen to progress some performance upgrades. I've read all the threads which are really useful but don't answer some questions I have.
I do not want to sacrifice reliability or efficiency and reckon the first mod is replacement headers from Kleemann. Why this first? Well I've looked at the standard headers which are probably fine for an engine that needs de-tuning to obtain the 360bhp required by Merc design, but look like they originate from a 1960's cast iron design on a standard car. The Kleemann replacements look the business, so...
Question 1:- Can just the headers be replaced or are downpipes also required?
Question 2:- Do the downpipes connect to the standard cats?

I'm looking to have these fitted by my local racing tuning specialists who are good guys, so I presume there is nothing that could cause problems? (Question 3)

I don't want to sacrifice the smooth quiet sound when cruising, but it would be nice to have a little more crisp note under acceleration and the odd pop and crackle under de-celerration - what can I expect? (Question 4).

Finally, is there anything I've overlooked?

Cheers
Dave
 

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Sadly Woolly has passed away
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It depends totally on what you want to do. On a drag-strip, you can throw as much money as you want to at it to shave fractions of a second off your quarter times. In reality, on our 'sheep chases' on twisty, winding mountain roads, when they are being thrashed, there is very little difference between a 55 and a well driven 200 - obviously manual box cars are the quickest of the lot.
 

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Start with deleting the secondary cats (post O2 sensor) and swapping the resonator for an x pipe. That's what I did to my car and the sound is great when accelerating yet still calm when commuting or idling. A little bit of crackle and pop when coming off the throttle too. You also won't need to flash the ECU to turn off the check engine light you would get by changing the headers.

Check YouTube for my channel "82DStock" for how my car sounds.
 

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If you still want to go with headers, note that the primary cats are actually on the same piece as our headers. Kleemann offers catless or hiflow cat headers. Either way, you will either need their tune or another company's flash tune to deactivate the check engine light.
 

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Discussion Starter #5
Thanks for the responses. The primary cats being so close to the headers (exhaust manifolds in UK speak), made me look further. It appears the outlet flange of the Kleeman header is a larger diameter than stock, so requires the downpipe anyway, and as the downpipe includes primary cats these would need replacing as well. It also appears that this will bring up a check engine light unless the Kleeman ECU remap is included (there appears a fix for this by moving the O2 sensors). Result of all this if I am correct is that it's not such a simple job of just changing the headers. Am I correct in this assumption?

Also, it would explain the secondary cat/x pipe mod instead which whilst not targeting the biggest restriction (headers) is a far cheaper option. Am I correct?
 

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Hi Dee4

I would start with just an Xpipe & leave all the Cats in place , You get a better noise out the back when you hit the go peddle but still quiet when at tick over , I have heard a 55 with the 2rd Cats removed & for me its too much very harsh , But if that's what you are after that's the way to go .

Cheers

Andy
 

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If he's looking to replace headers, a secondary cat delete wont be too much, though it definitely is noticably louder. I also did xpipe first only, but went back for secondary cat delete a month after. That being said, my girlfriend to this day has no idea I changed anything. It's still relatively quiet when driving around normally.

You are correct that you will need an ECU tune. There are companies who can do it wirelessly over the Internet. Even on a dyno if you want so they can tune to your car specifically.

Here's mine:

 

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That's a really good sounding car! Not too over the top, but definitely throatier and a refined, yet aggressive sound!:Beer:
 
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