hemp ... hahahah ...

"Turtle" it cant be that bad !!
if its a 2.5" roughly its abit big for a 1.6 littre engine (stock engine nothing changed)
2" to 2 1/4" should be ok..

Any body correct me if im wrong what i know is (assuming ur engine 1.6)
2.5" will give you top end power ..
2" to 2 1/4" give u lower power .. as it gaves more back pressure.

just do a tune up on ur car,
thorttle body + injectors cleaned out (as u take the throttle body, might as well the injectors, as they close by ).
adjusting tappets, and fresh new oil filter, oil on engine and gearbox .. roughly kinda major servicing..

see how it goes.. usually car feels much better after that

Good luck buddy