That depends on the mod, mine was to run the exhaust through the middle of the car to do this i had to widen tunnel rip of sierra suspension and make my own suspension then the boot had to be alterd so then it went on and on. But thats how it goes you start one job and then you think i might as well do that while you are there hopefully saving you time in the future. Then while the scuttle was of to get the exhaust in i thought i would fit mini wipers and then i thought i would change the heater fan for a micro fan, then why dont a change the position of the battery the fuse box, coil , water bottle , expansion tank , intercooler, oilcooler, ABS block, brake servo motor , petrol tank, petrol pump, petrol filter, Then fit new nose cone, make new boot lid, new seats [old ones dont fit now] , now got to make new bonnet, new vents in side of car, find a new place to fit radio, new place for ECU as its under glove box and when some one calls me on my phone the ECU cuts out . Then i thought now the exhaust runs through the middle i better run the petrol pipes down the out side not over the top of the exhaust, I think thats it , now all i have to do is retrim it and paint it im pushing it to get it to stafford more likly pushing it there.
Paul.