I installed these when we did the heads and cams.
They work great. They helped the car to start up better and as stated they provide a better spark.
You may see a gain of 1 or 2 horse but that is not good enough reason to run out and buy them. They are yellow in color.
I know a few people that swear their cars are running stronger after having swapped them in.
2002 True Blue Mustang GT M5
309 rwhp 320 rwtq tune by Big Shot Dyno
Best: 12.8 @ 109 mph
2004 Cosmos GTO M6 (1 of 366)
530 RWHP 510 RWT Tuned by Back Street Performance
Best: 11.33 @ 129mph