Unless you're stuck with them due to your location, I'd skip the cats.
They're restrictive, smelly, and create a massive amount of heat, not to mention the cost and added complexity.
Real estate under these cars is at a premium.
I agree, the X-Pipe would work very well at the current crossover location.

I bought an 8.8 today out of a Lincoln Aviator.  7.3 open but no matter.  I am putting in a Torsen T-2R.  I am almost positive unless someone here changes my mind. 

Since I moved back to Northwest Arkansas in 2020 after 8 years in way up NorCal my buddy who helped me a lot 14 years ago with this car passed away a few years back.  He built hotrods of all sorts.  He built my Frankendiff....by the way I think it is sold for 1200.00.

Anyway, I don't know anyone local really anymore.  The service companies are all big truck or 4x4s.  No one seems impressive.  I don't know if the Torsen is just routine for any competent diff tech or do I need to find someone that is more familiar with this type affair. 

I was thinking I might just pull the guts, clean it up and ship to Defined Autoworks.  I really don't want to add to his load getting this project completed though.

If you're buying a new diff, any competent drivetrain shop should be able to set it up to specs.
I'd think there would be several reputable 4x4 shops in your area that could do it.

I thought studs were the one place you shouldn't use anything that would affect torquing

I've always used anti-sieze on wheel studs, and never had a problem using factory torque specs.

This is a hellcat engine in a miata lol

I'm not sure you can describe that as IN a Miata. LOL

The factory design makes the cooling system work easy, overall.  A lot of the car is built like a racecar or very fancy kit car, with lots of aluminum extrusions and rivnuts setup to re-purpose Jaguar/Ford parts.   Makes it easy to adapt to my will.

The front and rear 1/3 of the car have full ducting/bracing flat floor plates that bolt on/off.   Makes life easier for ducting it all.    The middle of the car is also flat-ish, it looks a lot like a late model Corvette, but with even more aluminum everywhere.

Engine bay has tons of room for everything but the engine. I had to pull some sound deadening off the firewall and trim the heat shielding.   I then put gold heat reflection foil on the whole firewall and transmission tunnel (err, torque tube tunnel) then reinstalled as much of the OEM heat shield as I could to help reject as much heat as possible.  Clearance for the engine is about 5/16" to the rack, 1/4" to the firewall, 5/16" to the crossmember and 3/8" to the cowl.   So the engine can basically go EXACTLY here, and nowhere else.   Headers have miles of clearance, other than some subframe modding in one area, and they're well clear of the steering, etc.

I'll end up with a BIG intake tube to make sure the LT4 can breathe, but I don't think it'll be too bad.   I'd like to add some brake cooling ducts up front at some point as well. 

Once the heat exchanger is mounted I'll sort out where hoses need to go, then probably order some high density foam to seal it all up around the edges and force the air to go exactly where I want it.  That's how Aston did it stock and makes sense overall.

I have a spot for the dry sump tank, and I think I can reuse the OEM power steering reservoir, along with about 90% of the OEM AC lines and the entire low pressure power steering setup (lines + cooler) so that saves a lot of work.   I -might- be able to make the OEM coolant reservoir work, which would really make my life easier.   If all that goes well I just need to stuff the Radium breather tanks somewhere and fit the intercooler pump and tank, both of which will probably go where the passenger side airbox was stock (OEM it had dual airboxes).

Such a cool build Blake.  I'm looking forward to seeing this thing on the road. 

Your suggestion for foam board has me thinking I may use it for ducting in my racecar.
It looks like it would be easy to cut and bend, and cheap to replace in the event of damage.
I looked at it online, and there seem to be a lot of different types.
What are you planning to use?

Damn, sorry to hear about the damage. Glad it wasn't worse.

I'm sure the Mustang was a bit more comfortable though. 

Out of curiosity, does the spec twin have sprung hubs?  McLeod was saying to balance the flywheel, pressure plate, and intermediate plate all together.  Still seems really shitty it doesn’t come that way.

That's just weird. 
Way back in the late 90's I bought a McLeod 12" long style clutch for my Cobra.
After the machine shop balanced my crank, he mounted the flywheel, then the clutch, and balanced each separately.
I remember him saying that neither needed anything more than a tiny correction to get them perfect.

The RXT I bought for my FD I got slightly used.  It was the earlier style with the dedicated McLeod aluminum flywheel.
Maybe the previous owner had it balanced, but I didn't see any signs of it on the pressure plate.
It looked pretty much brand new.  I think he sold it because he wanted a heavier flywheel, but it obviously had very little use.
At any rate, I've never had any noise or vibration from it that I've noticed.