I would put the heat shield on if you have one or can fab one up. The X-pipe even out the flow and cancels out some of the noise. I used flanges back at the mufflers so you can take the whole system off from the headers to the muffs to pull the trans if need be.
Any crossover, X or H will help, but those Flow 10''s aren't much more than an old time glass pack for quieting the exh. I run the 3 chamber long case flows.
*****update***** That one bolt middle passenger side in header is leaking. Unreal to get to!!! Thought. Only I’m lift? Also. Car is very cold blooded wt no clutch. Suggest more gas in cold start or just crank? How these Buicks like to be massaged?
I hate that damn bolt lol. Seriously never want to deal with that one again, especially on driver side.
Do you still have no choke on it? If not your gonna have to let it warm up decently before driving. Don't ruin the clutch just because your in a hurry.
Totally cool letting warm up. Just cranks several times before caught. Didn’t know if I pump gas few times or just crank until fires up? This bolt suuucks