Sharing the below list I received from a customer service agent which shows what modifications are accepted and declined under the insurer Quotemehappy.
Quotemehappy Mods List:
Adapted For Disability ACCEPT
Additional Airbags Fitted ACCEPT
Additional Seating DECLINE
Additional Windows DECLINE
After-Market Exhaust System approved for road use ACCEPT
Air Conditioning ACCEPT
Air Filter ACCEPT
Alarms/Immobilisers/Tracking Devices ACCEPT
Add to vehicle security, not modifications.
Altered Pedal Configuration ACCEPT
Awning - Upgraded ACCEPT
Awning - Added ACCEPT
Badges Indicating Increased Performance ACCEPT
Biodegradable Fuel ACCEPT
Bleed / Relief Valve ACCEPT
Blueprinting DECLINE
Bluetooth Kit ACCEPT
Body Coloured Bumpers DECLINE
Body Kit DECLINE
Bonnet Bulge ACCEPT
Bored-out Engine DECLINE
Braided Brake Hoses ACCEPT
Bull Bars ACCEPT
Bumpers - Alloy DECLINE
Bumpers - Chrome DECLINE
Bumpers - Steel DECLINE
Cabriolet Conversion DECLINE
Camper Van Conversion DECLINE
Car Phones ACCEPT
Carbon Fibre Bonnet DECLINE
Carburettor Changed DECLINE
Catalytic Converter Removed ACCEPT
Ceramic Coating/PPF See Ceramic Coating/PPF page for more information
Changing to a Convertible DECLINE
Chassis Changes DECLINE
Chipping - Engine Management System Changes DECLINE
Chromed Engine DECLINE
Climate Control ACCEPT
Cooling Fan - Added ACCEPT
Cooling Fan - Upgrade ACCEPT
Cruise Control DECLINE
Dashboard Changes DECLINE
Dashcam ACCEPT
Debadged ACCEPT
Decals/Stickers ACCEPT
De-Handled ACCEPT
De-Locked ACCEPT
Door Poppers ACCEPT
Driving Lights ACCEPT
Dual Controls DECLINE
Dump Valve ACCEPT
EcoTek Valve ACCEPT
Electronic Ignition ACCEPT
Emergency Services Blue Light DECLINE
Engine Chip 00-10% inc BHP DECLINE
Engine Chip 11-25% inc BHP DECLINE
Engine Chip 26%+ inc BHP DECLINE
Engine Tuned DECLINE
Engraving - Custom DECLINE
Exhaust System Changes ACCEPT
Exhaust System Changes - Cosmetic ACCEPT
Exhaust System Changes - Cosmetic And Performance ACCEPT
Exhaust System Changes - Performance ACCEPT
External Racking DECLINE
Fibreglass Panels ACCEPT
Flared Wheel Arches ACCEPT
Flared Wings ACCEPT
Fog Lamps ACCEPT
Front Spoiler/Air Dam ACCEPT
Galvanised Chassis ACCEPT
Gearing Change ACCEPT
Graphics/Decals - Decoration/Non-Advertising DECLINE
Graphics-Customised Promotional/Advertising DECLINE
Hand Controls ACCEPT
High Level Brake Light ACCEPT
High Roof ACCEPT
Hoist ACCEPT
Indicators - Added ACCEPT
Indicators - Uprated ACCEPT
Induction Kit (Non-Turbo) DECLINE
Induction Kit (Turbo Vehicle) DECLINE
Infra Red Controls ACCEPT
Intercooler - Bigger ACCEPT
Intercooler - Front Mount DECLINE
Interior Changes DECLINE
Internal Racking DECLINE
Internal Shelving DECLINE
Lambo Style Door Conversion DECLINE
Larger Speakers ACCEPT
Light Cluster changed ACCEPT
Locking Wheel Nuts ACCEPT
LPG Conversion ACCEPT
Magnetic/Removable Signs ACCEPT
Manifold ACCEPT
Miscellaneous Engine Alterations DECLINE
Mudguards ACCEPT
Murals DECLINE
Neon Lights DECLINE
Nitrous Oxide Kit Fitted DECLINE
Non-standard Engine DECLINE
Non-standard Re-spray DECLINE
Oil Pressure Gauge - Added ACCEPT
Oil Pressure Gauge - Upgrade ACCEPT
Other DECLINE
Overdrive ACCEPT
Paint Work - Non Standard DECLINE
Paint Work - Race Replica DECLINE
Painted Signs (Greater than 25% of side and door) DECLINE
Painted Signs (Under 25% of side and door) DECLINE
Parking Sensors ACCEPT
Petrol Tank Changes DECLINE
Pop Up Roof - Added DECLINE
Pop Up Roof - Upgrade DECLINE
Power Boost Valve ACCEPT
Push Button Start ACCEPT
Quick Shift Gear Lever ACCEPT
Rally Lights ACCEPT
Rear Roof Spoiler ACCEPT
Rear Spoiler/Aerofoil ACCEPT
Rear Valance ACCEPT
Refrigerated DECLINE
Restrictor DECLINE
Right Hand Drive Conversion DECLINE
Road Conversion DECLINE
Rock Sliders ACCEPT
Roll Bars ACCEPT
Roll Cage DECLINE
Roof Rack NO REQUIREMENT TO DISCLOSE
Satellite Navigation Equipment NO REQUIREMENT TO DISCLOSE
Screen Changes DECLINE
Seatbelt Harnesses ACCEPT
Seats - Custom DECLINE
Seats - Removal ACCEPT
Seats - Replacement ACCEPT
Side Skirts/Sills ACCEPT
Side Steps ACCEPT
Slick Tyres DECLINE
Snorkel ACCEPT
Spoilers - Multiple ACCEPT
Sports Steering Wheel ACCEPT
Spot Lights ACCEPT
Stage 1 Head DECLINE
Stage 2 Head DECLINE
Stage 3 Head DECLINE
Stage 4 Head DECLINE
Standard Engine Replacement ACCEPT
Steering Change DECLINE
Strengthening Brackets ACCEPT
Stripes ACCEPT
Strut Brace ACCEPT
Sump Guard ACCEPT
Sunroof ACCEPT
Supercharging DECLINE
Suspension - Airbag/Hydraulic DECLINE
Suspension - Other DECLINE
Suspension - Uprated/Lowered/Stiffened Springs & Dampers DECLINE
Suspension Changes DECLINE
Tail Lift ACCEPT
Tent Boxes (Treat As Accessory) ACCEPT
Throttle Bodies Conversion (Non-Turbo) DECLINE
Throttle Bodies Conversion (Turbo) DECLINE
Tinted Windows ACCEPT
Towbar ACCEPT
Transmission Changes ACCEPT
Transmission Guard ACCEPT
Turbo Boost Controller DECLINE
Turbo Timer DECLINE
Turbocharging DECLINE
Twin Carb DECLINE
Unleaded Fuel Conversion ACCEPT
Upgraded External Mirrors ACCEPT
Upgraded Front Grille ACCEPT
Upholstery Changes DECLINE
Uprated Actuator DECLINE
Uprated Anti-Roll Bars DECLINE
Uprated Belt/Varieter Kit DECLINE
Uprated Brakes ACCEPT
Uprated Cam ACCEPT
Uprated Clutch ACCEPT
Uprated Fuel Injection DECLINE
Uprated Fuel Pump ACCEPT
Uprated Head Lamps ACCEPT
Uprated Headlight Bulbs ACCEPT
Uprated Stereo Systems DECLINE
Vinyl Wrap / Rubber DECLINE
Water Injection System ACCEPT
Water Tank(s) DECLINE
Wheel Spacers DECLINE
Wheel Trims ACCEPT
Wheelchair Clamps/Straps ACCEPT
Wheelchair Lift/Ramp/Winch ACCEPT
Wheels - Alloy ACCEPT
Wheels - Carbon DECLINE
Wheels - Magnesium DECLINE
Wheels - Wire DECLINE
Wider Tyres DECLINE
Wider Wheels DECLINE
Winch ACCEPT
Wind Deflectors Can be treated as an accessory
Wipers - Added ACCEPT
Wipers - Upgrade ACCEPT