is this true?i want to change from 2.25 to 2.50 would that increase my eng temp by a lot?for those who have done bigger exhaust system have you notice bigger temps in engines.thanks

I have never heard of such a thing.

it will increase the eng performance plus increase the noise. Mandrel bends & an X pipe works well & in addition glasspacks alonside the leaf springs will allow you to use more freeflowing (louder) regular type muffs up front & still have adequate overall noise control. Dynamax hemi turbos get good reviews here & cheap parts house "cherry bomb" glasspacks have outward punched louvers & do not neckdown where the nipples are welded to the main case & are cheap & do work.

I think someone who said that got it backwards, smaller pipes will increase back pressure and flow rate making the exhaust stick, stay, in the exhaust system longer making the motor work harder to go the same MPH
I've had to lean motors down when running open exhaust versus closed to get the same AFR

Engine coolant temperature or underhood engine temperature? I can see a larger exhaust increasing the underhood temp but not the coolant temp.

On your deal are you running a SB or BB?
If BB I would go to a three inch exhaust and not waste my money on enlarging the system a 1/8 inch
I have a BB Dart that I use to bracket race, I saw a ET decrease of 12.23 to 11.39 in the 1/4 mile running the car with a 2 1/2 inch system with a set of the old Corvair Turbo mufflers with side pipes exiting in front of the rear tires to removing it It went from 109.5 MPH to 117.7 MPH with at E.T. change also with no other changes
My last pump gas hot rod had a full length to the rear bumper three inch exhaust on it, it change from running 7.02 ET at 95.4 MPH in the 1/8 mile to 6.99 at 95.6 MPH by removing that system
The exhaust system size can matter

Yeah, that does seem backasswards somehow? I always thought that a larger or open exhaust would tend to lean things down. Hence the "myth" of the higher coolant temp. making no changes to the carb.???