Jeep weighs 5k lbs with tall gearing. Stuck using a single 3" exhaust with a cat. I'd like to shift at 6k and run a low stall or a really tight higher stall. I always thought the AirGap was too restrictive on a 408 so I instantly dismissed it. Something about it only flowing 250ish cfm and the heads could flow more. But I'm hearing different now and it shows in dynos that it makes great torque. Wondering if the 4bbl M1 is able to make around 540tq before 4500rpm? Narrowing cams to something around 224-230. Something on a wider LSA would be nice for check engine lights and smog.

From reading up around the web the last year or so you guys seem to know what's what, so I wanted to hear from the folks here first. I'm not 100% on a 408 either, PIE has a vortech kit that looks pretty good and I've got a 212/212 110 .563 cam I could throw in the stock block. If something happened and I lunched the 408 I'd be pissed. Blow a stock 5.9 not so much No idea how a centri would be vs 408 for low end. Thank you!

This is what I've got:
IMM Magnum heads
4bbl M1
Doug Thorley tri-y 1/58 headers-dual 2.5" Y to single 3"
26lb 4 hole injectors
SCT
1.7 RR's
58x52mm TB