Flash you have a few options for tuning, always multiple ways to skin the cat of course. I'm going to say this up front though in my opinion, 8 PSI, on what looks like a turbo similar in size to 16G, is going to REQUIRE larger injectors. You should install a Walbro 642 pump and get a 1:1 referenced FPR. These are a "must buy" for turbo conversions imho, and any kit that doesn't include a 1:1 is questionable right out the gate. Additionally, I highly suggest a "boost by gear" electronic boost controller, something like the turbosmart eboost2, fantastic bit of kit that lets you shape the boost onset curve and set differing boost levels by gear, as well as set differing boost presets, so you can run your "commute" map, say 4 PSI, "play" map say 6 PSI, and "kill" map 8 PSI.
1: Use TuneECU for base fueling. Zero out the L tables completely and the F-L switch table. This will get you simple single table tuning, but, it wont be able to provide enough fuel alone to compensate for 8 PSI. To compliment this, you can install the RRFPR, preferably one with an adjustable rate of gain. To tune this, I would hold the waste gate open at first so you get zero boost. Tune the F-table to get your N/A portions perfect. Once that's done, hook up the waste gate on just the spring pressure, whatever that is, a lot of turbos use springs @ 3-4 lbs stock. Now, this is where it gets tricky because your going to get some part throttle boost with the displacement of the Rocket. You'll have to retune the whole F-Table in TuneECU. At some point, you'll reach a max enrichment value in TuneECU where it wont let you add more fuel, if you're still lean, you will need to increase the rate of gain on the RRFPR, and retune the F-Table again. Rinse and repeat this process until its all setup working properly at your desired boost level.
2: Install a PC-V, AT, and GM 2 bar MAP sensor wired into the AUX input. Connect the speed sensor so you can do "by gear" tuning. With this method you can leave the L and F tables totally alone in TuneECU. Just tune it using the PC-V on the dyno by using RPM/MAP instead of RPM/TPS mode. Ensure you do BY GEAR tuning, you're going to build boost at different RPM and rates in different gears, this is important to get a perfect tune! Start by adding 50% fuel in the 8PSI areas, taper it down to +10% in the onset of boost areas and +5% in the RPM area JUST before boost onset. The 5% will smooth the transition and avoid bucking (common problem with Forced Induction conversions). You want to be working from too rich to too lean, so be generous when starting off, and start on LOW boost. Limit the AT control to like +/- 10% and leave it on at all RPM and all throttle positions over 2%. Ensure your MAP values in PC-V software extend to like 16 PSI, dont stop at 8 PSI in the table, and anything over your target boost level should be dead rich. This is insurance should your diaphragms in the boost controller or waste gate rip and cause an overboost situation. I say this from personal experience, you REALLY don't want to do a pull, and find you hit the motor with 25 PSI instead of the 15 PSI you had it set to, it ends badly lol.
3: Install a standalone. Most will turn away at this point, BUT, for the same amount of money as option 2 you can get a micro-squirt or megasquirt 3, a full standalone that has VASTLY more power than the Keihin ECU does. This is, technologically, the best option, though most won't do it. There is a TON of support for these ECUs online, and they have literally powered everything from remote control vehicles to championship winning race cars. They can adapt to any engine for any purpose, and they are far more flexible than the high dollar MOTEC/AFI etc ECUs.
4: Install some BIG injectors, like 680cc or 720cc injectors. Zero out the L table and F-L switch table. Do all your tuning in TuneECU. You won't need a RRFPR for this method as the injectors are so big TuneECU will have the flexibility to provide the required fuel. The problems with this method are that straight alpha-n, which this is, can sometimes be challenging to tune right and, you have no acceleration enrichment control.
4a: All the same as method 4, but use Tuneboy instead, it has a provision for a 2 or 3 bar map sensor, so you can keep using the L table and get perfect fueling with nothing but the stock ECU!
Hope this helps and gives you some suggestions you haven't already thought of. Good luck with your
trike quad, I really had a lot of fun on my last turbo conversion, I went the Megasquirt route, as the platform didn't have anything like Tuneboy available.
Regarding intercoolers, there is a LOT of misinformation out there, people who understand some of the theory but not enough of it. The most important dimensions are forward facing area, the least important is thickness. The more forward 1/2 of the intercooler does 3/4 of the cooling, so by doubling the thickness you can get some more cooling, but if you instead increased forward facing area by double you'd get vastly more cooling power.
Then there is the type of end tanks, the most commonly listed and sold ones are garbage. 1st image is what you usually find for sale, 2nd image is the better type. Second type has a lot less pressure drop and is more efficient at cooling:
