New Member from Idaho. Could use some coaching.

[nsmall]

2) Are TTI Headers generally considered the best headers for these cars as far as having the best blend of fit, performance, clearance, ease of installation? What finish is typically recommended? Is 2.5" considered an optimal exhaust size, even with a future 375HP build? Muffler recommendations? Also, the exhaust tips are corroded and need to be replaced. Any recommendation on OEM-like exhaust tip (that don't have the OEM price?)

TTI...yes, 2.5 if you want low end power...yes, I am happy with ceramic coated, I have flowmaster super 44s...NOT Quiet, but thats the point.  If you think OEM tips are expensive dont look at TTI.  Problem is if you are going with 2.5 all the way out, then go down to 2 inch tips...defeats the purpose of 2.5 headers. 

[7212Mopar]

Try Accurate exhaust for the SS tips. Classic Industries might have them too. TTI tips are nice but expensive. Cast aluminim Rallye are 17" wheels and not 15". Most will go with 8" wide front 4.25" BS. Rear can be same size or go with 9" wide 5" BS. Just Google Yearone Rallye and lots of pictures. If you have the stock Rallye center caps you can reuse them. The 17" Raylle wheels will fit Dr. DIFF 13" Cobra brake kit but not the Brembo kit.

[Brads70]

Thanks! That's a cool site.

Dr. Diff's Stage 2 Front Brake kit looks pretty interesting. 11.75" of Front Disc brake power over the 11" drums. Worthy upgrade? Would probably be a good time to convert to power brakes too. You did mention though instead using OEM parts. Are you talking about going to a junk yard and doing some pulls instead?

I'd love to see pictures of 15" and 17" wheels on challengers. Please post guys if you have pics...

Congrats on getting a car!
If your local yard has some older cars I would try and get the pin type caliper mounts.
"You'll also need a pair of rotors and caliper adapters (a.k.a. brackets) from most any '76-'79 B-body or 79-up R-body (St. Regis, etc.) Be careful when perusing the boneyards for theses, as Mother Mopar pulled off quite a bit of "badge engineering" in this period, resulting in some B-bodies carrying traditional C- body nameplates. The sure cure: check the VIN tag. Find an R, W, X, or S as the first character, and you're home free."
https://www.allpar.com/history/mopar/brakes/disc-main.html

For the exhaust tips, do some research! I found most just expand the pipe on the tips to get to 2 1/2" which restricts the flow. If your going to all the time and expense of going to 2 1/2" or what ever else  don't put a " cork" on at the end with the tips that have a 2" pipe expanded to 2 1/2"
Rear disc brakes .... unless your building it to autocross/road race I think they are a unnecessary expense.  Drums will work just fine in the rear. I had the smaller drums on mine for years and it worked just fine with the above stock disc brake set up. The only thing I found was pad selection for autocross or heavy braking was horrible and brakes faded quick once you get some heat in them. Maybe now pad selection has improved, I don't know? ( I,m now running Viper Brembo's and DrDiff small rear discs)
Power brakes.... I'm still running manual brakes . They work ok. I'f your engine is not stock it may not make enough vacuum to power the disc brake set up Again DrDiff has the M/C and adapters you will need.

[Dakota]

3) Wheel and tire sizes recommendations. I need recommendations and pictures for wheel/tire sizes for a 70 A66 Challenger. I'd like a little of a staggered look, but nothing that looks too far from stock. I plan to get cast aluminum 15" Ralleyes, but not sure of what backspacing for front and rear I should go with. Also, tire size recommendation? Tire brand recommendation (the "de-facto" choice is BF T/As).

Welcome to the site from Buffalo, NY! 

Regarding wheels and tires, you might want to look through the thread on the link below to see what others have done.  I've probably spent more computer time on this topic than anything else I've done with my car.   And I'm still thinking about it.

https://forum.e-bodies.org/wheels-tires-brakes-suspension-and-steering/12/e-body-tire-sizes-what-fits-whats-too-big-what-looks-good/4016/

[RUNCHARGER]

These are JY spindles, caliper adapters and new rotors and calipers. They worked great. I used a manual master cylinder and I thought it worked great. I don't think you need a power booster but lots of people like them. The calipers and rotors were off a 79 New Yorker I believe. Thats the JY rotor in the photo but I bought new ones before running the car.

[kawahonda]

Thanks guys.

Exhaust:

What do you think about something like this for the tips? Doesn't look like much expansion on the inlet. Do you guys think this would hurt performance? https://www.ebay.com/itm/2-5-Inlet-Quad-Square-Out-Exhaust-Tips-for-Dodge-Challenger-1970-71-72-73-74/263071422616?hash=item3d40475898:g:5Y0AAOSw~e5ZW5kP

For mufflers (mine comes iwth pinholes so they should be replaced), I'm looking for something that's going to give the 340 a really nice tone and growl, but certainly am not looking for glass pack-like noise. Any recommendations here?

Brakes:

I just got back from the junk yard, and didn't see any older Chrysler vehicles. How does doctor diff's Stage 2 Front brake kit compare to the factory 11" oversized drums? Regarding a booster or not, I guess I just need to drive the car "as-is" for a little bit to get an idea of whether or not I'll demand it or not. The 11" drum on the rear should be plentiful I would imagine.

Wheels:

Not sold on 17's after I've seen some pics. Much prefer the 15's. Would be nice if there was a Ralleye in a 16" wheel...that may be the ticket. If there's no 16" ralleyes, then it's going to be 15" Ralleye Steelies for sure. Hey, at least I saved some money, and I could probably reuse all my center stuff! For the 15" Ralleyes, I suppose I can just mimic the stock backspacing for whatever Dodge did with their own 15s in 1970?

This is an earlier A66 model that came with 14" ralleyes (ugh). Would have been nice if it started off on 15s.

[Brads70]

Those tips look good and not restricted ! 

[nsmall]

Those tips are a fraction of the cost of TTI and dont look like the restrict flow.  Not sure of the quality, but $125 and free shipping

[kawahonda]

Can you guys do me a favor if you have the stock tips? can you measure them and let me know what you came up with. I'd like to make sure that the tips on the Ebay link will fit like a glove. Something I'll definitely snatch.

[Morty426]

Can you guys do me a favor if you have the stock tips? can you measure them and let me know what you came up with. I'd like to make sure that the tips on the Ebay link will fit like a glove. Something I'll definitely snatch.

NOS Tips and aftermarket tips measure OD 1 15/16" - very much doubt a near stock 340 is going to be restricted by these. 

Also all A66 cars came with 15" rallyes in 1970, never heard of an early car getting 14" wheels.  If you have a broadcast sheet that shows14" tires that would be interesting. 

Congrats on getting the car

[kawahonda]

Thanks for your reply. I will get new 2.5" exhaust. Planning for a future 375HP build. Do it once, do it right! 

Not true on early a66s. Early ones came with 340 decal on hood and 14" ralleyes. Car was built in early November of 1969. Many other owners are claiming the same. Dodge did a rolling change to metal hood badges and 15" ralleyes sometime during the month of November. Search for it.

[Morty426]

Very interesting.

Many years ago I had an A66 4 speed car that believe was early since it had no holes in the hood for the badges however my car did have 15" Rallyes (which I still own)

Now my 71 Challenger 340 is a 14" hubcap car 

[kawahonda]

Hi guys,

Brakes should definitely be at the top of the list. I'm convinced that I don't need a booster and I'm convinced that my 11" drum if rebuilt and adjusted properly, would probably be pretty sufficient for the time being!

Where do I begin with a good "going through" when it comes to the brakes? Anyone sell any kits, and could you guys put together a parts list/links for what's usually required?

Right now the brakes are kinda binary. It's either "barely enough" to "holy shit!". There's a range in-between, but it takes some practice.

[RUNCHARGER]

I always do the 3 flex hoses, M/C and wheel cylinders on an unknown car. Brake lining too if they look rough. 11 inch drums have manual adjusters so you have to keep on that. Carefully check all the steel brake lines as well and with the age of these cars it is usually a good idea to just change them as well.

[kawahonda]

Cool, any recommendations/links of where these are? So far:

3x Flex Hoses

M/C and Wheel Cylinders...I assume a rebuild kit or a flat out replacement?

Brake shoes

I'll also want to look into having the drums turned.

Those seem to be the "for sure" things. I will certainly check the lines. I have reason to believe the car only has 68k miles, so I wouldn't expect things to be too bad. Underneath is rust-free.