An engine is a big air pump. The more you do to get air in, and through, and out of the pump, the better the pump works.

Keeping it simple: Adding the larger diameter exhaust is part of the equation. Also modify the airbox so it has cool air intake and install a high flow air filter. These two will provide improved performance throughout the power curve: Better low-end torque, better mid-range operation, better acceleration, cooler running engine; slightly better milage. Overall, there is less stain on the engine to operate, hence these will increase the engine's longevity.

As for cams, heads, etc. etc., if these are added, the whole engine should be balanced and blueprinted, to include better bearings, larger oil pump, larger oil pan, larger water pump, larger radiator, larger fan or electric fan[s], larger alternator, and battery [possibly two], along with necessary upgraded wiring, as well as leger and stiffer motor mounts and tranmision mount beefed up transmission/clutch to include larger pan and a cooler, beefed up U-joints, beefed up rear-end to include larger cover and cooler, new sport springs, new stiffer shocks/struts[and strut bearings], larger anti-sway bars, strut tower brace and lower unibody brace, new stiffer suspension bushings, rims with larger diameter and width and better and wider tires [Z-rated], plus larger rotors and and larger calipers plus better brake pads, and heavier brake lines. Inside the car there should be better seats and upgraded safety harness [five-point], maybe rollcage, not to mention gauges to keep track of your investment. also, modify steering and steering wheel for quicker and more precise steering, and add better lighting. And don't forget that all the fluids should be high performance as well. Oh, and to keep it running its best, more frequent maintenance.

THINK: Do you want a dependable daily driver with modifications to make it perform somewhat better, be more comfortable to drive, and have the car lasts [and not cost a fortune to operate], or do you want to drive a race car on the street [and beat your body .. and wallet .. to pieces]?

Be smug, let them laugh, keep the money in your pocket, invest it wisely so you can retire at 50 [when you can really have fun and not get in trouble]. After all, isn't that what Volvos are really about. And women like men [not boys] that can think about tomorrow, and have big .... wallets!