I have a magnaflow on my focus. they give great power gains and an amazing sound. not like all those kids at school i go with who have hondas with cheap exuasts that sound like a fart in a mud puddle. the magna flow goes for bewteen 400-500 dollars brand new. so it should be worth about 150-300 in good shape. Ive looked up the statistics for it and on an spi they claim up to a 20 hp increase on the cat back. I havent heard anything bad about magnaflows at all. they have a good reputation.