with some air filters and a performance exhaust how much power do you think they put out roughly ?

matt

 

125 bhp if fitted with a sun strip

 

I herd they are good for 400bhp with not alot of work and on std internals.

 

Thats with clear indicators and lexus lights

 

and a ironing board on the back,
Although to answer your question i would guess 280-300bhp

 

Depends what model R34 you refer to..
Assuming you mean the GT-R, a minimum of 3" exhaust would give you roughly 15-20bhp.
Filters would give you another 10-ish bhp.
You'd be looking at 300bhp.
But it would be alot more responsive than standard.