I'm running my set of SSD Marine injectors since the third week of June, along with the exhaust off the '94 C2500 (3" down into the 4" head pipe out a 4" 45* elbow angled down and part way out in front of the rear axle (NO muffler). Things I noted so far vs. the injectors I pulled (assumed the ones I pulled were factory installed new with 210K miles on them when pulled, no way of knowing the prior owner(s)'s maintenance or lack thereof)
(1) These injectors are running much cleaner than the ones I pulled, I don't roll coal like I used to when I mash it from a stoplight, just a short burst of black smoke that quickly clears as I build boost/speed. On my favorite 3/8 mile long uphill on-ramp onto I-80, if I roll into the throttle so I'm spooling the turbo at the bottom of the ramp so that I'm floored a third of the way up, it just gray hazes after the 3-OD upshift and keeps on pulling so that when I merge in at the top of the hill (70' gain in height over 3/8 mile with most of that the last 1/4 mile) I'm rolling at 85 MPH. The old injectors I was lightly black smoking the whole way up and merging in at 73 MPH.
(2) Definitely feel more seat of the pants power, whether due to the injectors, or the better breathing from the bigger (and seven foot shorter) exhaust allowing quicker spool up of the GM-8, or a combination of both, not sure.
(3) My weird TCC unlock at coast under no load problem has lessened noticeably (but is still there when coasting down long, steep hills with the cruise control on on the highway) most likely it was a combination of worn IP (still on the replacement list) and worn injectors creating an "either on or either off, but little in between" injection metering event.
(4) My fuel mileage has increased only slightly in highway mileage (about .75-1 MPG) on my round trip from Lincoln to Denver to Castle Rock (1200 miles) two days after I installed the marine injectors and the new exhaust - I'm attributing that to a still worn IP and the need for a good fuel mileage tune on the ECM (hint, Slim Shady) - and is the same or down in combined/city driving (another 1100 miles since I got back from Denver) - I attribute THAT to I can't keep my right foot out of it because that short, straight exhaust that dumps out underneath the Burb sounds SO damn wicked when I get on it under load and on boost and the turbine whine as I spool the turbo!
(5) NO white smoke at cold start up even, on the morning last week when it was 44* out. Also, it fires right off before it turns over one revolution.
Say what you will about Walt and SSD, but I've always had good luck with the quality of his products and with his business ethics and integrity in my dealings with him over the past 7+ years - including his telling me who his vendor was when I needed some pieces individually from a kit, that he sold and that he couldn't break apart to sell to me what I needed and didn't carry them as separate parts, so I could contact the vendor to see if I could get them individually and shipped directly to me - which they did at much lower shipping cost than shipping them to their distributor (SSD) to be reshipped to me.