is the M1 the only performance mod you'll have on it?
if so, like already stated, you may not notice it as much. I had CAI, bored TB, full 3" exhaust, and tune before i did the M1 and i could instantly feel the difference. but i dont know how it would be on a stock engine.
'98 Grand Cherokee 5.9L V8
-Stock suspension, 235/75R15 BFG AT's, AR767 rims with 4" BS - Fastman 52mm Throttle Body, K&N FIPK Gen 2, Kolak Exhaust, DMH Cutout, DT Headers, M1 Intake - 8300k 9004 Hi/Low HID's, 8000k H3 Off-Road Lamps - Rockford Fosgate P8002 and P4004 amps, 2x 12" Kicker CVR subs, Kicker SS56.2 components in Q-Logic kickpods, Front and rear Punch components, another set of components in the sound bar, 3600 watts total
The M1 Allows more air flow, so if your using a stock TB, your only getting in so much air, thus a bottle neck. Yes there will be some power gained, but the M1 is to be coupled with a TB and free flowing intake of your choice. Even then if you want your low-end power back a turtle is going to be needed for the M1. I'd rather suggest a stock intake thats ported or a "ported kegger".
Well I planned other mods as well such as a larger TB and headers coupled to a Kolak exhaust.
it just so happened that the M1's were in short supply so I thought I get one before it would be hard to get so to say...I do realise that mods tend to add up to eachother though!
I think you'll see more of an improvement than the others have said , If your intake is stock , the probability of a leaking plenum is extremely high w/o a hughes plate . The vacumn leak alone in a power loss . M1's have a one pc design , no plate , to me , that's worth the cost right there .