Port-match and smooth the lower/upper intake — or swap to the better-flowing 1999+ tube intake. Cheap stroker-tier mod.
The 4.0L intake comes in three generations:
Port-matching the stock 91-98 intake to the head gasket and smoothing the EGR boss is worth a couple HP and is free if you're already doing a head gasket. The bigger upgrade is the 99+ tube intake, which bolts on with minor fuel rail and TPS work to any 91+ head.
On a stroker the 99+ tube intake is essentially mandatory — the 91-98 cast intake becomes a flow restriction. Cost is whatever you pay for a used JK/TJ tube intake (~$80-200 at a pull-a-part) plus new gaskets and a fuel rail crossover. Some builders combine the 99+ intake with a Renix-era throttle body location adapter to keep linkage geometry.
Don't waste money on 'high-flow' aftermarket intake manifolds (Sprintex aside) — the 99+ OEM is as good as it gets without going to a custom sheet-metal intake.
| Part | Vendor | Est. price |
|---|---|---|
| 99+ tube intake manifold (used) | Pull-a-part/eBay | ~$150 |
| Mopar intake gasket set | Mopar | ~$60 |
| Fuel rail (99+) | Mopar | ~$80 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.