Here's the best picture that I have of the front with the stock Ray's and the 275/35 - 15mm spacer. I have noticed no loss of power, but I also added a Stillen CBE a few days after I got the new tires. Actually, everything feels just about like it did before and I am very pleased with the setup. My speedo ended up being about 1 mph slower than my GPS says I am travelling so I know it is pretty close as well. Others will say that the 275 front, 305 rear is too agressive but I disagree. I did go to 9.5/10.5 when I got my new wheels which made the tires look just about perfect on the wheels. Let me know what you go with and good luck!
AZ