Flowtech LT's are the best bang for your buck as they can be had for under $300 not coated and $400 for coated.
Here are mine. Flowtech LT's with o/r x pipe and magnaglow dumps.
http://svt4u2try.com/media/LT3.avi
If you need one, just look at the engine serial number(located on the left side of the block on the bottom near the oil pan) and call 1-800-FORD-SVT and they will send you a new tag.
I would find out why. To me that is a big deal because it leads to me some repairs were done or some rigging was done by someone who has no idea what they are doing.
I have been running Flowtech LT's for 2 years with the Ford gaskets and no issues.
Ask him when the Flowtech seals don't hold, is he willing to re-do the job again for free?