So I sold by 99NB1 (non sport suspension, 15" wheels) and bought a 05 mazdaspeed. The mazdaspeed seems to have less feel than the NB1. I'm not sure if this related to the quicker rack, or if it is related to the big (and somewhat heavy 17" racing harts). Could also be alignment. I kind of dig how the racing harts look. The only other difference is tires, I ran yokohama s-drives on the 99, and have bridgestone re760 on the 05. The mazdaspeed has 100k less than my NB1. I also see that miataroadster sells solid steering rack mounts. Trying to decide where to start... It could also just be my memory (ownership did not overlap).

I am particularly curious to hear from folks that have either swapped wheels, or driven both cars back to back.

 

Swapping to 15's makes a huge difference in driving feel

 

MSM rack is actually not quicker; just has less turns lock to lock and a wider turning radius to accommodate the 17" wheels. So steering feel should not be any worse and you've already highlighted potential areas to address: alignment, tire compound, wheels etc..

 

Racks and systems are identical, so your issue is in the tire width or alignment.

 

I'd think a power steering setup with 100k less miles might make a difference too.

Don't I remember the steering limit on the MSM being limited because of the intercooler pipes? 17s should be the same diameter with those lo-pros bro.

 

Do they even make low pro enough 17s to have a 23" diameter? Except for like nexans and shinkogowas?

 

205/40-17 is 23.5ish, as close you will get, unless you want 195?

 

Wow, thanks for the super helpful info! It sounds like I should start with tires and then perhaps a good alignment. If I can find light 17" wheels am I better off with 17? I assume the goal of going with 15" is unsprung weight. Does anyone know if the RPF01 15" fit over the sport brakes?

 

Also, is there any way if I go to 15" to adjust the rack stops and improve the turning circle? I definitely notice it is much wider! I would like to avoid replacing the rack...

 

You're either replacing the rack or taking it out to modify it, so you might as well just swap it. You'll have a replacement NB rack out of the car to clean up while your car is still running, then it's just a simple swap.

This is also only a choice if and only if you can modify the MSM rack to decrease the steering radius. Not sure if it's even possible.

 

I don't recall the exact difference but I do know it wouldn't be a simple modification. The pinion and tie rods are the same IIRC but there would be machining to do on the rack. It's not just some stops to remove or cut out. The MSM rack is ****.

That said, OP - the only place it will behave differently than any other NB power rack is getting into tight parking spots with the school bus turning radius.