Been playing with NA cars still on our in house dyno, using HKS header with HFC fitted;
Dyno plot below is the dyno plots of a stock car v HKS header/de-cat/exhaust system(no tune) and tuned with ECUTEK
BLUE STOCK CAR
GREEN BOLT ONS (HKS manifold with HFC/decat pipe/exhaust system)
RED BOLT ONS + ECUTEK TUNE
We hope the ACE header (manifold) with the 350 Collector will work even better when it arrives.