CS, you shouldn't need double relays to make the nod work with two sets of LEDs. First, the reason (though I have not confirmed this) that the two LED setup doesn't work is that the side lamp needs the low impedance of the front bulb 'turn' filament as a route to ground, and doesn't get this with a front LED.
HOWEVER, if you only use a 3157 LED in the front, you'll get hyper-flashing ANYWAY, so you'll need a low-ohm load resistor in series to fool the BCM into thinking there's a filament there, drawing current. In that case, you will again have your low impedance route to ground, and thus the side marker should flash - even when using DBG's simple splice method.
[NOTE: the way (from inspection) the DBG splice method works is that the blue lines are the +12V interrupted signals to the front turn filaments. The black wires are grounds. Thus you splice the ground of the side marker, to the 'trigger' (+ve) wire of the front turn filament.
THUS, when the turn/flash signals are off, the black wire is grounded through the front filament and the side marker lights. When the turn filament is switched ON, both wires to the side marker are +ve and so the side turns off, but then lights again when the the front goes off - which is why it alternates with the front turn.] NOVA will be back next week with another unsolicited documentary!
Ah interesting. My take on it was, the addition of the 2 diodes on top of the relays would then allow you to use whatever 3157/4157 bulb you wanted LED or halogen, with the relay method and it would still work.
Or alternatively, I figured adding the same 3-6 ohm resistors per branch of 3157/4157 would work as well if I went LED that route.
I finally decided I'm gonna go with some tinted tail lights (will tint some clear and spray it on). And I wasn't comfortable with that for the longest time because if I did, I would want to go with brighter bulbs. Well I found them finally not too long ago, for a price I was willing to pay.
Picked up some 3157 cree, with projector LED bulbs. Kinda like this:
And one like this for the reverse light:
The red 3157 LED bulbs have already arrived and are they ever freakin bright. My fiance thought they were ridiculous compared to lighting up just a plain halogen 3157 I took out in terms of brightness.
The white reverse light without the peripheral smaller LEDs is awesome as well, but it needs a resistor as well or it will be dimly lit when the car is running.
The guy I'm dealing with for the bulbs has been fantastic about everything except slow shipping, albeit free (and prices were better than Stunner Lights even though I didn't have to order an entire package/kit, and you can order as much or as little as you want, and not just an all or nothing kit with bulbs you probably won't want, and some bulbs you might want but aren't provided, and SL is not willing to sell piece by piece).
Furthermore, the guy I'm dealing with has thrown in resistors for free (so far 5 for free, and may end up being 7 if I do the the front turn signal delete). If I did, I'd mount an amber 3157 in the top corner parking light above the projector headlight. I'd also tap the turn/hazard circuit, to include the 194 LED in the fender marker light to alternate flash, and add an LED strip that would go around the edge of the headlight housing. So basically the front turn signal would be deleted (I'd simply paint it off black for now, and perhaps add some auxiliary lighting in the future), graft a 3157 socket ring onto the back of the existing plug for the 194 in the top corner parking light, and add an LED strip on a parallel branch circuit to the fender light. Which is what got me doing some turn signal research.
I've done some measuring, and I should be able to run the LED turn signal strip the way I want to and could even setup an Audi-esque LED DRL treatment as well. Just debating now if I want to add an LED strip for DRL type function since I deleted my DRLs when I went with the 55W HID headlights. When I decide I'll order the LEDs. But still gotta get this breather tank project done, and it's been wintery lately and looks like it'll stay that way till at least next week when I'm back in school.
Oh, and thanks again for being a sounding board for ideas with your expertise as usual TS!