1998 SAAB 9-3 repair Question catalytic converter

Engine Performance problem
1998 Saab 9-3 repair Question 4 cyl Front Wheel Drive Automatic

The used car I just bought, knowing this shortcoming, has less power than reasonable. It seems act like a standard transmission starting in 3rd or rather like the Dodge/Chrysler "Fluid Drive Assist" of the late 1940's. Starting in 3rd gear range is actually an electronically selectable - 'SNOW' - option with this transmission. So the problem may be that this "option" is not being deselected with the push button control on the console. However I think a bad Cat converter is also a possibility. After the car gets above 15 to 20 mph it seems to be almost OK, but does not seem to have the response of a Saab 900 that I has about a dozen years ago.

The electronic 'miles per gallons display' (real time calculation the with most recent 20 miles traveled as a base rate) shows 20 mpg which is may be below the advertised 27 mph highway. I have only had the car for about 40 miles so data is insufficient.
AT 71,000 miles I do have my reservations about the poisoned Cat Converter diagnosis. The car seems to have been treated well to average and seems to have lived most of its life in the southeast and driven at 6500 miles a year average never did work hard. Tires are new Pirellis, air filter is new, have yet to check fuel filter, all fluids well attended and at least one change of calipers.
I bought this as part of a charity fund raising promotion and paid about 1/2 the Edmiond's listing. On the Southeast coast of Georgia there are few people who know what a Saab is or would want one, so I did do some charitable thing but will have something that I could keep around probably as long as my advancing years.

Now FINALLY to my question:
If I have to replace the Converter what is the situation with these "Magnaflow Catalytic Converters" that I see advertised for $60 to $90?

The other converter prices seem to be in the $400 to $500 range and seem to incorporate most of the I/O piping rather that the bare cut and weld converters that are the pictured Magnaflow units. Assuming that the price differential is accounted for by the additional Header/exhaust piping, . IS the Magnaflow unit one which will function properly and provide the necessary back pressures and flow rates to keep the engine healthy and happy?

NON TECHNICAL QUESTION:
I notice you offer solicitation for donations. Don't really know what your expectations are but I realize that Free Advise is often Worth the Price. So does what I donate now set my future precedent?
Look I am not being cheap so I am only submitting $XX. XX** amount edited by buddycraigg** as I am never sure which web sites are still active as so little on the I-net is date stamped. So based on your response I could an ex post facto adjustment,
So am waiting your reply as I go to have the front tires balanced as there seems to be a thrown balance weight.

Regards
Peter L.