Ace A350 header vs JDL 4-to-1. Green = stock, Orange = Ace A350, Blue = JDL 4-to-1. All dynos on ACN91.
The "dip" on the Ace header in this graph is an anomaly. Here's a full set of Ace dynos to verify.
The JDL 4-1 completely obliterates the torque dip. Long story short, the JDL makes the same peak area under the curve as the Ace from 6500-7400, which is important if you're shifting at redline and want maximum acceleration. If you want maximum bang for your buck for top end power, go with the JDL 4-1.
The A350 has a vastly larger midrange powerband, yielding larger overall gains area under the curve, but comes at a premium price. If you want the best powerband available NA, go with the Ace A350.
Both headers are engine limited up top, rather than flow limited.
For FI results with a supercharger, see this thread, that compares a Ace A350 vs Gruppe-S header, both on a JRSC + HBP + Ethanol. The Gruppe-S header is on a straight E85 tune, whereas the Ace A350 is on a Flex tune with E70. Straight E85 tunes will always make more power than a Flex tune.
http://www.ft86club.com/forums/showp...postcount=5027
CSG has packages available for both the JDL 4-1 and Ace A350 4-2-1 headers that include tunes.
*edit*
Been informed this is the 4-1 header. Post corrected.