Here's the history of my RB M1 intake, along w/ experience with a couple of other intakes wink

Hughes did welding & porting in plenum to convert mounting pad from TQ-style to square-bore 4150 style
I did additional porting in plenum and runners
I added epoxy in runners to correct port alignment issues due to core shift
Car ran 126 MPH w/ a 1" Super Sucker spacer using that intake
Epoxy lifted due to 10% ethanol in pump fuel

Swapped the M1 for Victor intake w/ my own plenum work and some light runner cleanup; no room for spacer due to limited hood scoop clearance; that particular intake made about 10 HP more than an unmodified Victor on Dwayne's dyno, and 5+ HP more than the M1 w/ spacer did, IIRC, on a 610+ HP combination
Car picked up by .05 ET and .5 MPH with no other changes, which is right in line w/ the difference seen on the dyno

Tried to open runners of M1 up to match the Hughes CNC-ported "semi-MW" Victors I purchased, but the casting didn't have enough meat
Had local welder build up top of intake runners to allow for raising the ports enough for those Victors... ugly, ugly, ugly
My subsequent porting wasn't my best work (I rushed through it too quickly, instead of taking my time) and I hated the way it turned out

Sold those Hughes CNC heads and started over with new standard-port Victors that Dwayne finished for me, leaving the size a true "standard" port
Tried to use Belzona to shrink the M1 runners back to standard... ended up with a horrible & unusable mess in the runners that I won't be able to fix easily, if at all
That intake is basically a really expensive (my time and other people's labor) aluminum doorstop now

Took an out-of-the-box Trick Flow intake and spent less than 30 minutes doing basic plenum and runner casting cleanup (not even port-matched); made 680-ish HP with a 1" Super Sucker spacer... guess-timating it's 10+ HP more than that M1 would make if it was still usable
I've got an untouched Trick Flow I can swap out to check if any work I do to the first one shows improvements on the track

Unfortunately for me... This is The Way... I go about things

2021 Challenger 6.4L Scat Pack 1320
100% stock: 1.680, 11.894 at 113.75 (DA 175 ft)
weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)

1973 Challenger 452 ci street/strip [2008]
pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)