Impact of mods on insurance quote - Classicline

Got a very decent quote from Classicline for my GTA and I am now seriously looking at fitting the race twin exhaust and boost control mod. Does anyone know what their view is on such mods and whether it's a no go or the premiums go through the roof - I've bottled phoning them as I don't want my bubble to burst!

My premium was raised by £30 for the year when i disclosed my mods Race twin exhaust, ART induction kit & boost bypass valve. Mine was worked out off performance increase which they have bracketed by 10%, 20% etc. increases. I dont know if thats an industry standard way or just my insurance company's way of assesing premium increases?

Couldn't hold out so I phoned them - the quote I had would have increased by only 25% - on £177 I felt that was more than acceptable. They did though say if I was going to go down that route that another insurer they had which came in at £188 said they wouldn't increase the premium at all! So, all sorted and I can install the mods at any time without it affecting my premium!! Cool!

[BIG_MVS]

I'm with classicline as is Juzz, think I only pay about £170 a year with Stainless Exhaust and 17" Alloys declared as mods. I have a set of samco boost hoses and DG's boost mod to go on and will ring them first, to see if it changes anything.

Didn't change anything for me - so you should be Ok.