I bought a 68 Mustang convertible last fall. This is my first classic car since I was in high school 44 yrs ago. I had a '64 Nova and a '67 Camaro.
Just before I put it in storage for the winter, it developed a leak in the exhaust manifold. Now that I am working from home, and have some time on my hands, I am going to get it out of storage and start working on it. I plan to start by replacing the manifolds. Nothing fancy, 289 with dual exhaust. From what I can tell the rest of the exhaust is in good shape. Now for the age old question; The car is stock right now, with the original engine and transmission. Do I just replace the existing exhaust manifolds or do I improve by putting in headers, which will include modifying the existing exhaust system. I am taking a hard look at this because once I start improving, I can see myself wanting to go to disc breaks, a four barrel carb........ Keep it stock, or improve the ride. Pros and cons?

 

Pros to modding: Its fun, There is no limit, if done right the car will dominate on 90%+ of the modern car population.

Cons: Its expensive, it may devalue the car typically "found in time capsule still has original engine oil" will fetch much more than a better driving, better handling more fun to drive modded version.

What do you plan to do with the car is there a goal in mind?
How often do you drive it?

In my case I wanted a classic car that I could daily drive that has impressive performance for its age and in many cases will outperform a modern vehicle. I wanted this because they are unique and most people are excited by something like this and it gives me something to do.

In my opinion you've got a convertible so its not really something that I would try to turn into a performance beast. Do you want it to sound different if yes then go headers and mod exhaust to work. If you like how it sounds then replace with original. Now the two items that I would recommend changing would be the front brakes go disc... I dont know what size wheel you have but I would try to find a better tire with some performance to it.

 

It is a convertible with an automatic transmission. I am looking for this car to be more of a cruiser, driven on weekends, between May and October. Sometimes to work on nice days. Not trying to turn it into a performance beast. I was thinking of front discs, some Craiger wheels and better tires for sure. I am torn between trying to retain the car as it was made or making it a little more comfortable, fun and safe to drive. I don't really care about resale.

 

The sound is fine as is. Not trying to change that.

 

Just go original headers, if not cracked then just replace gaskets. headers alone wont improve Hp or drive quality.
For a weekend fair weather cruiser You'll want a good quality set of disc brakes at least in the front something like 12"+ rotor size
if you are going to go with new wheels try to go 17" this is because the 17" wheel will allow any brakes you want and will open the door for a high or ultra high performance tire. 17s should be no issue with the 68. A UHP tire like the pilot sport 4s will allow for a very significant improvement in cornering and stopping distance over what you have now. But 50 series is the widest they make the sidewall.You would have to compare to what you've got now to figure out what it would do to ride height. If unacceptable there are plenty of other options in 17" that would still be good performance

 

Thanks. That's good advice on the brakes, wheels and tires. Will going to a 17" rim require low profile tires? I don't want to do that. I was thinking of going to 15" or 16" wheels.

 

You'll have to do some measuring. How small are the wheels now??

 

The wheels are 14"

 

they looked larger I thought the 68s had larger wheels stock than the 66. I guess not

The bare minimum would be 16s. 16s will get you into some fair tires that will be better than the dismal choices you have now.

the goal would be to maintain a total tire height equal or close to what you have now. If you increase tire height you'll need to find a different driven gear for the speedometer likley not a huge deal.

A bit lower profile will reduce sidewall flex and squirm from the vehicle improving cornering and stability.

So now its up to you how to proceed. So A tire that is 245/45/r17 is to be fitted to a 17" wheel, The width of the tire tread is 245mm the height of the sidewall is 45% of 245mm (this is a 45 series tire). So search around and see what wheel back space you need and how wide of a tire you can fit under the car in a particular size say 16 or 17. Then hit up tire rack and look for something that isnt total crap in a 16" or 17" wheel and you'll be able to calculate total tire height based on series and width in mm. Obviously if you go 16" you'll be able to run a taller sidewall. In my opinion it would be a shame to run anything numerically larger than 60 series after all that work.