Well, the cast manifolds are a cork in its arse, which works like heads with restrictive ports. For a stealth street engine you want a semi smooth idle. The 340 bumpstick should work fairly well. You do need a dual pattern cam to aid the exhaust. Another trick to aid low lift exhaust flow for the street is to cut the exhaust seats and valves for 40° seats. This aids blowdown with lower RPM. Yes the racers find gains with 50° seats but are using high lift cams and rockers.
