i just purchased my miata today! i plan on getting to my v8 conversion asap.
question for you guys, whats the best/popular rim size you guys are using? also tire size? i want my ride to sit as low as possible hom much does the v8 (ls3) lower the car?

 

The most common wheel/tire size seems to be 15x8 or 9 rims with 225/45-15's (Hankook RS-3) or 225/50-15's (a few other brands). This combo will fit under most Miatas without much in the way of fender rolling. Also, good tires in those sizes can be had for under $150 a tire which is important in a car with over 300 foot pounds of torque.

As far as ride height goes, I believe you can lower a LSx conversion as low as you can a standard Miata. A Ford conversion can be lowered as low as possible as well if you route the exhaust through the tunnel as opposed to the traditional through-the-wheel wells method. Even with the traditional Ford routing you can still lower the car about an inch form stock.

6UL rims seem pretty popular although I've seen Rota RB's used a few times as well. While there's a lot of wheels available in 15x7 there's not many in 15x8 that are cheap. I would not go with a 15x7.

Welcome!
-Jason

 

My problem was getting the car high enough for clearance of the exhaust pipes. The Boss Frog kit really gives you no place but under the rear to exit the pipes. They show a hammer beaten pipe jammed through their dif. mount but it's ugly and sloppy. What you do for adjustable coilover springs will be what determines your ride hieght. I changed my springs out on all corners because I wanted more height and went with Good-Win-Racings 6UL in a 15x8 rear and 15x7 front. Then had them mount Toyo R888 tires in 235x50x15 in back and 205x50x15 in front and love the look and ride. Good luck with you project. Steve