Just wondering why the price point between the 270 Amp SP and 250 Amp XP is so large. I don't understand why I would pay $120 more for the same output at idle and 20 amps LESS at max. I know the XP has some different internals, but is it really worth the extra change?

The XP series alternator is a completely different monster. They are more efficient at producing power, have extremely good cooling technology and give you twice the diode capacity and over 6 times the rectification heat sink over a SP series alternator. Not to mention they are electronically silent so you will never hear engine noise due to the alternator. This is our little writeup on the XP series alternator page:

DC Power Engineering’s Proprietary XP Series alternators are built on the world’s first SC (Segment Conductor) alternator design. The XP series alternators are 20 percent lighter and provide a 50 percent increase in output than a conventional wound alternator. This is achievable by using rectangular copper for its stator, which increases the density of the windings from 45 percent to 70 percent. These patented technological advances have made it possible to increase the generation efficiency by 10 percent to improve fuel consumption and performance. The XP series alternators are capable of producing a minimum of 150 amps at idle at 200°F and can produce as much as 200 amps at idle depending on the vehicle application thus producing as much as 70 percent of it's maximum output at idle. All of these breakthroughs in technology have allowed the XP series alternators to be the most reliable, durable and best performing alternator on the market.

Thanks Kyle!