The problem here is that the comparison sites define it in one way, but it doesn't necessarily match the definition used by the companies that you get quotes from.
For example, Ensure appear on confused, but they define modifications as:
A modification is any alteration or change to the manufacturer’s standard specification for your car, including optional extras fitted to the car when new by the vehicle manufacturer or dealer, which improves its value, performance, appearance or attractiveness to thieves. This includes, but is not restricted to, changes to the engine, engine management or exhaust system, changes to the wheels or suspension system, changes to the bodywork, such as spoilers or body kits, paintwork or changes to the windows, such as tinting. It also includes any modifications or changes made by previous owners.
Please see below for the full list
Accessories
• Air Conditioning/Climate Control
• Altered Pedal Configuration
• Bull Bars
• Car Phones
• Dashboard Changes
• Hand Controls
• Locking Wheel Nuts
• Parking Sensors
• Removal of Seats
• Replacement Seats
• Roof Rack
• Satellite Navigation
• Sports Steering Wheel
• Sunroof
• Tinted Windows
• Towbar
• Upholstery Changes
• Wheelchair Clamps/Straps
• Wheelchair Lift/Ramp/Winch
Engine/Transmission
• Air Filter
• Blueprinting
• Bored-out Engine
• Chipping - Engine Management System Changes
• Exhaust System Changes
• Gearing Change
• LPG Conversion
• Miscellaneous Engine Alterations
• Nitrous Oxide Kit
• Non-standard Engine - different engine to original
• Standard Engine Replacement - same engine as original
• Supercharging
• Transmission Changes
• Turbocharging
Lighting
• Driving Lights
• Fog Lamps
• High Level Brake Light
• Rally Lights
• Spot Lights
Paintwork/Stickers
• Badges Indicating Increased Performance
• Decals/Stickers
• Murals
• Non Standard Paint Work
• Non-standard Re-spray
• Sign Writing
• Stripes
Spoilers/Body Modification
• Additional Windows fitted to side/rear panels
• Body Kit
• Bonnet Bulge
• Flared Wheelarches
• Flared Wings
• Front Spoiler/Airdam
• Rear Boot Lid Spoiler/Aerofoil
• Rear Roof Spoiler
• Rear Valance
• Roll Cage
• Side Skirts/Sills
• Strengthening Brackets
Suspension/Steering/Brakes
• Dual Controls
• Suspension Changes
• Uprated Brakes
Wheels/Tyres
• Alloy Wheels - aftermarket addition
• Alloy Wheels - manufacturers option
• Wheel Spacers
• Wheel Trims
• Wider Tyres
• Wider Wheels
Other
• Other - Not listed
And this certainly includes manufacturer's options