Exige - Toyota 2ZZ-GE 1.8l (Celica VVTLI engine + SC)
Elise - Honda K20 2.0l (Civic Type R engine + SC)
The Exige was 230bhp @ the hubs, around ~260-270bhp @ the flywheel.
The Elise is 277bhp @ the hubs, around ~300-310bhp @ the flywheel.
That doesn't paint the whole picture, the Elise is at least around 100kg lighter and has much more torque available everywhere in the rev range.
The Elise is a little harder and noisier due to the loud exhaust on it at the moment, but nothing night and day different as it's still a usable everyday car.
Performance wise, the Elise is miles faster.
Exige 0-60 + 0-100 = Low 4's + High 10's/low 11's.
Elise 0-60 + 0-100 = 3.x's + 8.5.
Neil.