Update: Definitive KZ650 installation of Delkevic 4-1 exhaust. I did it!!!!

Stock exhausts are designed to give the best compromise of sound and performance whilst still meeting the required sound limits of any particular country.
By this very nature it means that any stock exhaust (especially on older bikes) will be slightly restrictive and not be the best for all out power or speed which is why there is such a huge market for performance exhausts.
Fitting a decent , free'er flowing / less restrictive exhaust with the correct jetting if needed will give a noticable power and speed inprovement over stock.
As rule of thumb a 4-1 is best for all out top end whilst a 4-2-1 gives a stronger mid range.

In my opinion the biggest advantages of a header is lighter weight, hot rod sound, and cleaner appearance (for bikes with a tatty exhaust at present). Some make more power, typically at the top of the range, but not all. Particularly if running the stock airbox. Downside of headers are jetting headaches, low ground clearance, and inferior chrome and excessive noise on some models. I personally will pay more money for a bike with the stock exhaust.

On my old Concours I used ordinary anti-seize compound, not so much as a sealer, but to insure that the mufflers were easy to r/r when it was time to replace the rear tire or service the shaft drive stuff.

I bought the Delkevic exhaust system today and will be installing in myself. The stock exhaust pipes I have on the bike now are pristine, no rust. BUT the exhaust header bolts, thats a different story. Im thinking this may be an obstacle in taking off the old exhaust. Any ideas? Only a few bolts, nuts are rusted this badly:

pentrating oil and heat keep soaking and heat an let cool then repeat 6mm ones are a PIA.

Ignoble metals will rust first,(react with air/water oxygen) and contagious noble metals to corrode.
Your non stainless steel wire to hold the header wrap infect the other metal parts, you have to use a stainless steel wire.

Sacrifical anode

en.wikipedia.org/wiki/Galvanic_anode
en.wikipedia.org/wiki/Cathodic_protection

DFIGPZ wrote: pentrating oil and heat keep soaking and heat an let cool then repeat 6mm ones are a PIA.

Is there any way to take the studs out of the engine block and replace them with no rusted ones?

Yes, of course why not with the right tools and skills.

Scirocco wrote: Ignoble metals will rust first,(react with air/water oxygen) and contagious noble metals to corrode.
Your non stainless steel wire to hold the header wrap infect the other metal parts, you have to use a stainless steel wire.

Sacrifical anode

en.wikipedia.org/wiki/Galvanic_anode
en.wikipedia.org/wiki/Cathodic_protection

The bolts were rusted long before I put the wire on the wrap. The wire has been on the wrap for 6 months only. They are quite far from each other and I doubt there is any interaction.

Anyway, penetrating oil, heat and elbow grease it is!

I will report back with developments.

.....and stainless 6 mm nuts and bolts are available.

Scirocco wrote: .....and stainless 6 mm nuts and bolts are available.

Thanks. Right.

Where from? Do you have a link?

650Dude wrote:
Where from? Do you have a link?

z-fever.de/shop/en/product_info.php?info...n-edelstahl-6mm.html