N/A maximum? Is turbocharging the only way?

[eyore]

Well I had a series 1 Elise totally standard with 115bhp and supposedly 950kg and it felt waaaaaaaaaaayy faster than the MX5, so yes I absolutely agree getting rid of weight is probaly easier cheaper and better than chasing horsepower.

[Steve]

Heres a '90 at 206hp NA :
http://www.bigllama.com/miata/mymods.html

This is a good read :
http://www.solomiata.com/CheapHP.html

Heres the lightweight guy mentioned above :
http://lightweightmiata.com/beast/

[shaneh]

id say go with itb,s
thats what i plan on doing anyway. you can buy the full kit from a site called jenvey.
itbs and head work and get it revving to near 10,000 rpm haha.

http://www.youtube.com/watch?v=c2MTdigVyt4

[ger]

Well I had a series 1 Elise totally standard with 115bhp and supposedly 950kg and it felt waaaaaaaaaaayy faster than the MX5, so yes I absolutely agree getting rid of weight is probaly easier cheaper and better than chasing horsepower.

mk1 elise is 725kg not 950kg power to weight is roughly 160bhp per tonne (118bhp model)
Not much point chasing that weight from a 5, a basic turbo setup at 6psi should give you a similar power to weight but with more torque and you can keep your carpets and electric windows etc.

The bare bones mk1 mx5 with no extras is still 950 kg, thats no EW/PS/AC, cant see how you will get much lighter than that without changing panels or looking at tubular wishbones etc all much more expensive than bolting on some power.

[paulNA]

id say go with itb,s
thats what i plan on doing anyway. you can buy the full kit from a site called jenvey.
itbs and head work and get it revving to near 10,000 rpm haha.

http://www.youtube.com/watch?v=c2MTdigVyt4

itb's would be last thing on the list to upgrade, without serious engine work you wont really benefit from them that much for the money you have to spend on them