Both are corrosion resistant. Both weld cleanly in the right hands. Both handle the heat cycling of an exhaust system without complaint. If you are choosing between two well-made systems in these materials, you are not choosing between good and bad - you are choosing between two sets of trade-offs.
A titanium part of the same dimensions weighs roughly 40 to 45 percent less than its steel equivalent. On a system that runs the length of the car, that difference is measured in kilograms, and where the weight sits matters as much as how much of it there is.
Titanium gives a higher-pitched, more metallic note than stainless in the same design. It is not simply louder - it is a different character. Whether that is better is a personal judgement, and it is the reason many buyers choose the material after hearing both rather than reading about them.
Titanium conducts heat less readily than aluminium, which is why it is favoured for intake components on high-output turbocharged cars: it rejects radiant heat instead of soaking it and passing it into the charge air.
Stainless is more forgiving to repair and modify. Titanium demands tighter heat control, full inert-gas shielding and more careful handling, which is part of why it costs more. If you plan to change the system again, that is a real factor.
Weight and sound push one way, cost and repairability push the other. Neither answer is wrong. Tell us how you use the car and we will tell you honestly which one suits it.
