Can such a thing be found? About three years ago, I recall finding Internet promotional material for some kind of software fix that was supposed to increase horsepower and that was available for normally aspirated engines as well as turbo-charged.

My car's a '97 manual five-speed.
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Always looking at, reading, and thinking about something

Yes, there is. But the only 'upgrade' I would do is to get an ECU from Europe to plug into your car. This will get you more 'top end' speed, but useless for the USA with speed limits on high speed roads.

While your 5 speed may seem slow, it beats the heck out of the automatics on a race track, including low presure turbos. If all you want is a car that goes from 0-60, you own the wrong car. If you enjoy twisting and winding roads, you already have the best balance of engine and tranny offered by Volvo.

Klaus
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Always willing to listen, just not able to take direction.

Ah, well, if that was all I wanted, I'd be driving something else, but a little more horsepower would be welcome. My indie mech likewise informs me that "there's a lot to be said for factory."

So you recommend against a software alteration to the whatever it is in the system that has alterable software. Are there actually European ECUs that can be purchased for the non-turbo 850? IPD used to sell one some years back but no longer offers the product.

Yep, twisty and winding country and mountain (such as they are in this part of the world) are what I enjoy best when driving.
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Always looking at, reading, and thinking about something

I looked at Ebay in England and Germany, nada for a non-turbo.

I suggest you change the engine oil with 5W30 synthetic, new filter, flush the tranny with synthetic oil, add a couple of pounds of air to the tires, keep the revs over 2500 and just have fun! Oh, clean air filter and good plugs help.

BTW, 2nd gear at 5500 will get you a ticket in most states. Throttle up through the turns...

Klaus
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Always willing to listen, just not able to take direction.

If you want some more power on the NA, I suggest you consider replacing the throttle plate which has been extensively discussed. You will get a lot more response in acceleration from zero and at lower rpms.But not much more at higher rpms. Yes, you can feel it at long winding uphill driving. But mileage drops a bit.And keep your hot cold air intake flap valve operating correctly, or do away with it.