yes you can put a T5 in it BUT it depends how long you want it to stay there??? The minute you give it full beans you'll just sit still revving the t*ts off it!! As well as Sierra's these are a good conversion for the Capri with the huge engine bay. Given that the Boa is (IIRC) 196BHP and the Bob is 206bhp, the T5 was only built to cope with around 150bhp (standard output for the 2.8i Capper) so as you can imagine.... it will fit, but it won't be long till you're taking it out again!