Car hard starts, backfires. Retune?

Hey all. First post here after being a lurker for quite some time, didn't think my first post would be one that was asking for help but here it goes. As the title says after a plugs (TR6 .40 gap) and headers install my 98 Camaro hard starts (doesnt crank slow, just continues to crank) and if you don't cycle the key within 2 seconds or so and continue to try and crank it the car backfires hard. Very similar to a gunshot. Sometimes it'll start on the first crank and sometimes it takes a few tries and a few loud backfires before it takes off. After its started the car seems to run fine. Doesn't miss or backfire at idle or any rpm including WOT but it does seem to run a bit rich in comparison to before I put these plugs in. Previous plugs were shot, had a set of TR55s gapped at .50 that the previous owner left in for way too long. Other than the plugs only thing I touched was the tubes going from BBK shorties to TSP 1 7/8. All my O2s are there including the 2 in the y pipe. So I guess my question is is the tune the problem? Can going one heat range colder and a bit tighter plug cause this? It was suggested that I possibly cracked one of the plugs during the install but wouldn't it run noticeably bad during acceleration if that was the case? Any help is appreactiated.

List of engine mods if that helps
TSP 1 7/8
Torquer v2 113lsa with typical top end supporting mods (tuned by Cunningham)
MTI lid
Smooth bellow
BBK 85mm TB
LS6 intake
243s

Welcome to the site!

How's your fuel pressure?

Has it been tuned since the long tubes. They will cause the car to run rich if it's not tuned.

Part of it sounds like the fuel pump may be going out. Hence why jeff asked your fuel pressure probably.

Thank you! I don't have a pressure test gauge to attach to the Schrader valve but I can definitely get it tested. It's odd that this just started happening after the plugs. With the wrecked TR55s in there it fired right up no hesitation

I'm waiting for my tuner to get back from out of state on family business but it will be tuned shortly. I guess if it's in the tune that'll be dealt with while its strapped down. I just wanted to see if anyone else has had a similar issue while swapping to these plugs but on upon my search I couldn't find too much which was worrying. If it's the pump it's a good excuse to put a racetronix in it.

When you installed the ignition wires, did you hear/feel two "clicks" on each coil pack and one "click" at each plug? If not, you may want to run back through each wire to ensure that they are fully seated. Plugs are torqued to 11 lb.ft.? None of the wires are making contact with the header tubes?

The plugs are torqued to spec and nothing touching the headers but I don't specifically recall any clicking when reinstalling the packs. They did start to tighten and I guess felt like it "clicked" in but not twice, I'll recheck today. First time changing the plugs on a COP engine

I 2nd checking the plugs and wires.

How'd the previous plugs looked? oil or gas soaked? burnt?

They looked a bit burnt but not fouled. Don't know if this is coincidental or not but it seems the problem is worse during cold start vs when the car is at running temp. During cold start it's almost guaranteed to do it but I've noticed after its warm it starts much easier, there's a good chance it'll start on the first crank vs when it's dead cold.

Fuel filter ever been replaced?

Have you checked the fuel pressure at the rail yet? I didn't see if you post it.

May be an irrelevant suggestion, but also inspect/clean your IAC valve as carbon can gunk it up and cause hard starting or start then stall.