George,
I reported to the list a "backfiring" that had occurred at altitude.  I
typically fly at FL 230-250 and 70 LOP.   It was traced to the Unison
Slick Magnetos.  Both showed carbon deposits in the cap and corrosion in
the right magneto after 240 hours.  Slick was very cooperative in
replacing the magnetos.  I have acquired about 30 hours since then and
they perform beautifully.  I also have GAMI injectors.

Note:  I was also told to change the inline filter to the magnetos on
the TSIO-550.  I could only purchase a box of 10.  They should be
replaced every 500 or 1,000 hours depending on who you talk to.  So I
have several lifetimes of the filters.  I paid $29.46 each for them.  If
anyone wants one, send me a check for $20 and I will include the
shipping.  Part is a Balston DFU, Grade BX, filter tube, 8833-11-BX.

Contact me off-line at:

Carl Cadwell
Cadwell Laboratories, Inc.
909 North Kellogg Street
Kennewick, Washington 99336
(509) 735-6481
1-800-245-3001
Fax:  (509) 783-6503
Email:  carlc@cadwell.com
Website:  www.cadwell.com