I couldn't justify the price of a FAST 102 so I tried the Dorman LS2 intake at half the price knowing it will need some massaging as it's not perfect. Shown below is the process I went through to "port" it which was spent reshaping the runners. I did not touch the actual port size since my heads were stock, the ports match the heads already.

The car:
03 Z06 60k mi
BTR Stage 2 cam
Stock LS3 air bridge + card MAF on SD tune
Mamo ported LS2 TB
Dorman LS2 intake
TPS 1 7/8" headers, catted X pipe and Corsa Sport CB


Cliff notes on porting a DLS2 to a stock 243 heads:
1) DLS2 port width at the head matches that of the stock heads = not worth widening to the reported 1.1"
I had access to PORTED 243's with a port matched FAST 102 to those exact heads which DID show 1.1" head/intake port width AND that the intake porting was "angled".
2) The runner thickness at the area that needs the most removed is ~5mm. (drilled a hole and verified thickness at each runner).
3) The runners of the DLS2 and Fast102 look very similar in design/shape but the FAST has a substantial larger plenum volume (obviously hence the increased height which may allow slightly longer runners)
4) It seems like one engineer designed the upper runner half and someone else designed the lower flange half then glued them together...fairly poor transition between the two halves.
5) All said and done there was more material on the floor than I ever thought.

Ported FAST102 lower section on stock 243 heads (I borrowed this FAST to take some porting pointers)

Drilled a hole in all runners where most material will be removed to check wall thickness

The hole ends up directly in the corner of the runner

Put drill bit back in and verified wall thickness

Final product. Removing this much material you need to be careful. The wall can get paper thin to where light will shine through the plastic. I worked my way "UP" the runner focusing on blending the large runner radius to the smaller port radius. If you wanted to go nuts and make it perfect you could also fill in some low areas but what I did was 90% there that I didn't feel the need to spend a lot more time on this. I did NOT touch the original port opening here as I felt it lined up well on stock heads. More porting may be needed once heads get ported.

Here you can see I got too carried away on this one as it was my first one...lesson learned. This shows aluminum foil tape inside the runner as a backer to keep JB weld from dropping through. I also sanded then "hatched" around all holes to let JB weld bite. Once JB weld was solid enough but still pliable, I removed the tape and smeared more JB weld over the small holes and let it fully cure.

Not pretty but functional. I'll address aesthetics later.


Results below are the following (bold are the incremental changes) pulls done starting 2000rpm in 4th:
Blue = Halltech "Stinger" CAI (filter placed behind filler plate), stock C5Z MAF, Mamo Ported LS2 TB, untouched Dorman LS2 intake 381/334
Green = Stock LS3 air bridge + stock card MAF + SD tune, Mamo Ported LS2 TB, untouched Dorman LS2 intake 385/338
Red = Stock LS3 air bridge + stock card MAF + SD tune, Mamo Ported LS2 TB, ported Dorman LS2 intake 393/344

*Blue and Green pulls done on same day and same dyno back to back swapping CAI (Nov last year). Red pull was done on the same dyno this past Saturday.

I liked that the TQ curve is not just a peak gain but a gain across the whole pull. HP starts to gain around 4200rpm.


Resulting A/F graph. Since this graph we added some fuel up top to make it safer with no loss in power (dyno above are after fuel adjustments)

Porting the Dorman was worth 11hp/6tq. Just reporting my findings. I'd be curious to bolt a FAST102 on and see if there is much more to be gained. At the time FAST102 was and still is ~$900+. The DLS2 was $410 shipped. I believe I make at least 80% of what the FAST would give me with my combo. So I don't see a huge benefit to seek a FAST102 given the cost and I don't have any fitment issues or the need to shim the cradle/lower motor mounts.

 

I would love to see the difference between 85mm maf and ls3 card style. My tuner wanted to charge me an arm and a leg extra to tune for the new maf so I just had them leave it with the 85mm. '84 C4, 6.0, ls3 top end, 1-7/8" LTs with 3" mandrel xpipe exhaust, 220/224 cam made 420 rwhp. After I got it back I swapped to the LS3 maf and retuned it myself. Huge pickups, probably 15-20 rwhp from swapping mafs and adding a sprinkle of timing. +2 degs peak torque and +1 up top for a total of 26 degs. I am thinkinging the maf helps to the tune of 5+ rwhp on my setup.

 

Smitty, that's an outstanding post!

I like the pictures showing exactly what was done porting the intake. A++

It's killer to have dyno results before and after.

No question about results for porting.

 

All is well ~3 years later. Still going strong.

 

Would love to see how a ported Fast would compare on that setup. Supposedly there are gains to be had even on a stock motor. I didn't notice much if any difference when I went to a Fast on my original motor.

Its a shame the price of the DLS2 has skyrocketed so much and made it irrelevant compared to other intakes

 

I'm happy I got a DLS2 when I did for sure. Maybe when I get my heads ported I can try my DLS2 and my buddies FAST that has been port matched to ported heads.