I cannot post any pics as I killed my good computer. But, the Stock Nozzles are now made in India and so far as I have read they do not have the best rep for quaility control.
You can see the pics I have often posted in other threads that shows the Stock Nozzles have tiny holes drilled down the center of the Tip of the Pintel on the Spray Nozzles and are cross drilled up higher in the Nozzles with a larger Holes.
On my own Engine I found that both of those holes were entirely Plugged with Carbon and it was the same with most of the ones I have pulled at the Junk Yard.

So, besides the Made in India issue the stock Nozzles if not kept clean with Diesel Purges; I believe they are more likely to get clogged than the Monark or the Bosio Spray Nozzles.

The Monark Nozzles are Made In Germany and do not have the tiny drilled holes to get plugged up.

I would read some more threads there is a lot of info on them.

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84 300D, 82 Volvo 244Gl Diesel